[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

Grant Grundler wrote:
> Log message:
> 2.4.18-pa62 acenic-0.91+minor fix
> Jes Sorensen asked me to test his latest driver...besides
> one minor build fix in acenic.h it loaded and booted.
> 
> First time I tried the machine crashed. I didn't have /sbin/hotplug
> but CONFIG_HOTPLUG was enabled. May this serve as a reminder
> to others...

diff against whatever we had in our CVS before:
	ftp://ftp.parisc-linux.org/patches/acenic-0.91-ggg.diff

and the original tarball (drivers/net/acenic.[ch]):
	ftp://ftp.parisc-linux.org/patches/acenic-0.91.tar.gz

This line of output:
eth1: Enabling PCI Memory Mapped access - was not enabled by BIOS/Firmware

The driver isn't using pci_enable_device() and it should.
Jes is aware of the problem.

But I'm happy...another HP IO card supported by parisc-linux. ;^)

I tried to run netperf but netserver segfaults on parisc.
I'll rebuild to see if compiler changes have fixed netserver and try again.
Anyway, I need to figure out which other 1000SX card is connected
 to the switch.

grant

a500:~# modprobe acenic
acenic.c: v0.91 07/31/2002  Jes Sorensen, linux-acenic@SunSITE.dk
                            http://home.cern.ch/~jes/gige/acenic.html
eth1: Enabling PCI Memory Mapped access - was not enabled by BIOS/Firmware
eth1: Alteon AceNIC Gigabit Ethernet at 0xfffffffffb000000, irq 322
  Tigon II (Rev. 6), Firmware: 12.4.11, MAC: 00:30:6e:04:80:68
  PCI bus width: 64 bits, speed: 66MHz, latency: 128 clks
eth1: Firmware up and running
eth1: Optical link UP (Full Duplex, Flow Control: TX RX)
a500:~# uname -a
Linux a500 2.4.18-pa61 #4 SMP Sat Aug 3 01:00:08 PDT 2002 parisc64 unknown unknown GNU/Linux
a500:~# ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:30:6E:04:80:68  
          inet addr:192.168.0.21  Bcast:192.168.0.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:40 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:8951 (8.7 KiB)  TX bytes:1522 (1.4 KiB)
          Interrupt:66 

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Matthew Wilcox]

On Sat, Feb 08, 2003 at 03:27:46PM -0700, Grant Grundler wrote:
> > Kudos to John David Anglin and Carlos O'Donnell for realizing
> > PA 2.0 is not strongly ordered like PA1.x is.
> > Read appendix G or PA-RISC 2.0 Architecture (Gerry Kane) for
> > details on "Memory Ordering Model".

I'm confused.  This directly contradicts the comments in
include/asm-parisc/system.h.  If this needs updating, so does that.

> > I've uploaded palinux-20030208.tgz to dsl2 and will try to build
> > a binutils.deb with this change as well.

Is all that's needed to take the latest binutils from debian unstable
and rebuild it on woody?

> +++ arch/parisc/Makefile	8 Feb 2003 06:21:32 -0000
> @@ -32,6 +32,10 @@ CROSS_COMPILE := hppa-linux-
> +ifdef CONFIG_PA20
> +CFLAGS += -mpa-risc-2-0
> +endif

I've reverted this one.  We already have:

ifdef CONFIG_PA8X00
CFLAGS += -march=2.0 -mschedule=8000
endif

which covers the same cases.

> +++ include/asm-parisc/spinlock_t.h	8 Feb 2003 06:21:34 -0000
> +> I've attached a summary of the change, but basically, for PA 2.0, as
> +> long as the ",CO" (coherent operation) completer is specified, then the
> +> 16-byte alignment requirement for ldcw and ldcd is relaxed, and instead
> +> they only require "natural" alignment (4-byte for ldcw, 8-byte for
> +> ldcd).

That's interesting from an architecture PoV.  From my recollection when jsm
was debugging problems on the 710, PCX-S is the only processor which actually
enforces the 16-byte alignment restriction on ldcw.  So _practically_, we
don't need it unless we're supporting those old processors.

> +#ifdef CONFIG_PA20
> +/* PA2.0 is not strongly ordered. ldcw enforces ordering
> + * and we need to make sure ordering is enforced on the unlock too.
> + */
> +#define spin_unlock(x) \
> +		__asm__ __volatile__ ("stw,o  %%sp,0(%0)" : : "r" (x) : "memory" )
> +#else
> +
> +/* PA1.1 is strongly ordered. No issues here. */
>  #define spin_unlock(x)		do { (x)->lock = 1; } while(0)
> +
> +#endif

Actually... this may be a long-standing bug in our spinlocks.  There's nothing
to prevent gcc reordering writes around this assignment.  We need a barrier()
before the assignment, or maybe it'd be as well to do the assignment in an
asm() statement.

>  #define spin_unlock_wait(x)     do { barrier(); } while(((volatile spinlock_t *)(x))->lock == 0)

i wonder if this one was working around some obscure compiler bug a
while back.  I don't see why we need to cast to a volatile spinlock_t *
given that lock is already defined as volatile.

One final point.... up till now, we've been telling people it's OK to
run kernels configured for PA1.1 on PA2.0 processors.  This patch says
to me that's not safe.  Do we need our distros (yeah, I hear there'll
soon be more than Debian supporting PA) to ship 5 flavours of kernel
(PA1.1 UP & SMP, PA2.0 32-bit SMP, 64-bit UP and 64-bit SMP) rather than
the current four?

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[John David Anglin]

> That's interesting from an architecture PoV.  From my recollection when jsm
> was debugging problems on the 710, PCX-S is the only processor which actually
> enforces the 16-byte alignment restriction on ldcw.  So _practically_, we
> don't need it unless we're supporting those old processors.

I am pretty sure that any PA 1.x machine needs the alignment.

> > +#ifdef CONFIG_PA20
> > +/* PA2.0 is not strongly ordered. ldcw enforces ordering
> > + * and we need to make sure ordering is enforced on the unlock too.
> > + */
> > +#define spin_unlock(x) \
> > +		__asm__ __volatile__ ("stw,o  %%sp,0(%0)" : : "r" (x) : "memory" )

If you change the above to

  __asm__ __volatile__ ("stw,ma  %%sp,0(%0)" : : "r" (x) : "memory")

it should work on both PA11 and PA20.  The ordered completer is only
PA 2.

> Actually... this may be a long-standing bug in our spinlocks.  There's nothing
> to prevent gcc reordering writes around this assignment.  We need a barrier()
> before the assignment, or maybe it'd be as well to do the assignment in an
> asm() statement.
> 
> >  #define spin_unlock_wait(x)     do { barrier(); } while(((volatile spinlock_t *)(x))->lock == 0)

I think the volatile provides the barrier in my suggested version.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Randolph Chung]

> I think the volatile provides the barrier in my suggested version.

volatile would prevent reordering accesses to a particular spinlock, 
but does it ensure that code that happens after the spinlock will not
be reordered to happen before the spin-unlock?

for example, if we had:

volatile spinlock l1, l2;

lock(l1)
do something
unlock(l1)

lock(l2)
do something else
unlock(l2)

will gcc ever move the lock(l2) before the unlock(l1)? 

(for reference, see this thread:
http://lists.debian.org/debian-gcc/2002/debian-gcc-200210/msg00058.html)

randolph
-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Randolph Chung]

> lock(l1)
> do something
> unlock(l1)
> 
> lock(l2)
> do something else
> unlock(l2)
> 
> will gcc ever move the lock(l2) before the unlock(l1)? 

well, bad example, since l1 and l2 are both volatile, but in general,
nothing will prevent part of "do something else" to happen inside the l1
lock, right?

randolph

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Matthew Wilcox]

On Sat, Feb 08, 2003 at 04:56:08PM -0800, Randolph Chung wrote:
> > lock(l1)
> > do something
> > unlock(l1)
> > 
> > lock(l2)
> > do something else
> > unlock(l2)
> > 
> > will gcc ever move the lock(l2) before the unlock(l1)? 
> 
> well, bad example, since l1 and l2 are both volatile, but in general,
> nothing will prevent part of "do something else" to happen inside the l1
> lock, right?

I think it's even worse than that.  What stops gcc reordering:

typedef struct {
        spinlock_t lock;
        volatile int counter;
} rwlock_t;

static  __inline__ void _raw_read_lock(rwlock_t *rw)
{
        while (__ldcw (&(x)->lock) == 0) \
                while (((x)->lock) == 0) ; } while (0)
        rw->counter++;
        do { (x)->lock = 1; } while(0)
}

to:

        while (__ldcw (&(x)->lock) == 0) \
                while (((x)->lock) == 0) ; } while (0)
        do { (x)->lock = 1; } while(0)
        rw->counter++;

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[John David Anglin]

> > lock(l1)
> > do something
> > unlock(l1)
> > 
> > lock(l2)
> > do something else
> > unlock(l2)
> > 
> > will gcc ever move the lock(l2) before the unlock(l1)? 
> 
> well, bad example, since l1 and l2 are both volatile, but in general,
> nothing will prevent part of "do something else" to happen inside the l1
> lock, right?

Volatile would stop gcc from moving code across either the lock or the unlock.
A blockage is in fact implemented as an UNSPEC_VOLATILE instruction.
The PA 8000 has a large reorder buffer, so there are similar issues.
It's guaranteed that instructions will appear to execute in order on a
processor but the memory updates as viewed from another processor may
occur out of order.  To ensure that other processors have a consistent
view of whats happening, one must use ordered instructions for the lock
and unlock operations.  This will force all stores and loads inside the
lock to complete.  Further, if cache flush operations occur inside
a lock, you must also do a "sync" before unlocking to ensure that these
operations complete.  The ldcw insn is strongly ordered.  A load and
store on PA 2.0 can be made ordered with the correct completer.  Cache
flush operations are weakly ordered.  On PA 1.x, all load and store
instructions are strongly ordered, so ordering isn't an issue.

The current spinlock reset is done in high-level C.  So, gcc can move code
that that isn't dependent across the reset.  PA 2.0 processors can also do
the same.

Appendix G describes ordering in much more detail.  Hopefully, I haven't
butchered what's said there too badly.

The reordering that GCC does is conditional on instruction dependencies.  I
just reworked the handling of the PIC register restore in PIC code
because all the PIC register were not apparent in the initial scheduling
pass.  This is in 3.3 and main, but not 3.2.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[John David Anglin]

> I think it's even worse than that.  What stops gcc reordering:
> 
> typedef struct {
>         spinlock_t lock;
>         volatile int counter;
> } rwlock_t;
> 
> static  __inline__ void _raw_read_lock(rwlock_t *rw)
> {
>         while (__ldcw (&(x)->lock) == 0) \
>                 while (((x)->lock) == 0) ; } while (0)
>         rw->counter++;
>         do { (x)->lock = 1; } while(0)
> }
> 
> to:
> 
>         while (__ldcw (&(x)->lock) == 0) \
>                 while (((x)->lock) == 0) ; } while (0)
>         do { (x)->lock = 1; } while(0)
>         rw->counter++;

Nothing.  The reset needs to be a volatile asm.  This will stop GCC from
doing the above.  On PA 2.0, the processor can do similar reordering.  So,
the reset needs to be an ordered store.  Well, I think the scheduling
model tends to try to do things as early as possible, consistent with
not over feeding the pipeline.  However, I wouldn't rely on this to
get the instrunction order that you want.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

On Sat, Feb 08, 2003 at 11:23:03PM +0000, Matthew Wilcox wrote:
> Is all that's needed to take the latest binutils from debian unstable
> and rebuild it on woody?

Almost. It needs a patch too:
	ftp://ftp.parisc-linux.org/patches/900_order_hppa.diff

Just drop that in debian/patches before building the debs.
That patch applies clean to the binutils for unstable.
I don't even pretend to understand how to properly build
debian packages, much less binutils or "cross release" builds.
That's why I made the tarball for "testing".

> That's interesting from an architecture PoV.  From my recollection when jsm
> was debugging problems on the 710, PCX-S is the only processor which actually
> enforces the 16-byte alignment restriction on ldcw.  So _practically_, we
> don't need it unless we're supporting those old processors.

I don't care to find out the hard way.
I'd rather just comply with the architecture and not worry about it.
If someone can demonstrate a perf advantage or issue, I'll be
more receptive.

> Actually... this may be a long-standing bug in our spinlocks.  There's nothing
> to prevent gcc reordering writes around this assignment.  We need a barrier()
> before the assignment, or maybe it'd be as well to do the assignment in an
> asm() statement.

I've read the followups to this and I gather our spinlocks are very broken.
If someone tells me what the right fix is, I'll test on PA20 32/64 bit
and commit.

> One final point.... up till now, we've been telling people it's OK to
> run kernels configured for PA1.1 on PA2.0 processors.  This patch says
> to me that's not safe.

Only for SMP. I think for UP the rule still holds.

> Do we need our distros (yeah, I hear there'll
> soon be more than Debian supporting PA) to ship 5 flavours of kernel
> (PA1.1 UP & SMP, PA2.0 32-bit SMP, 64-bit UP and 64-bit SMP) rather than
> the current four?

Unfortunately yes.

OTOH, PA20 SMP still hasn't proven stable so maybe it's not worth
doing at the moment either.  Once PA20 SMP is stable, we could drop
the 64-bit UP kernels since most systems that *require* 64-bit are SMP.

thanks,
grant

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

On Sat, Feb 08, 2003 at 07:35:18PM -0500, John David Anglin wrote:
> > +#define spin_unlock(x) \
> > +		__asm__ __volatile__ ("stw,o  %%sp,0(%0)" : : "r" (x) : "memory" )
> 
> If you change the above to
> 
>   __asm__ __volatile__ ("stw,ma  %%sp,0(%0)" : : "r" (x) : "memory")
> 
> it should work on both PA11 and PA20.  The ordered completer is only
> PA 2.

Excellent idea.

In case it's not obvious to others, "stw,o" is an alias
for "stw,ma" with a Zero index value. But PA11 assembler
will grok the stw,ma properly.

I'll look at getting this into the kernel this week if someone
else doesn't beat me to it.  I'd like to test what I've got a bit
more now and get the binutils .deb availability issue resolved.

thanks,
grant

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[John David Anglin]

> > If you change the above to
> > 
> >   __asm__ __volatile__ ("stw,ma  %%sp,0(%0)" : : "r" (x) : "memory")
> > 
> > it should work on both PA11 and PA20.  The ordered completer is only
> > PA 2.
> 
> Excellent idea.

The reason I am so up on this is that in testing gcc 3.4 on hppa1.1 this
weekend I found a problem with the locking code in atomicity.h.  This
was the 16-byte alignment issue.  In reviewing the assembly code being
generated, I revisited how the lock reset was done and came up with the
above.

This is also relevant to locking in glibc.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc-cnrc.gc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

[parisc-linux] re: [parisc-linux-cvs] linux grundler

[John Marvin]

> o moved disable_sr_hash() from SMP to common code path so all
> CPU's (including monarch) have this disabled.

Huh? You didn't seriously think the monarch still had sr hashing enabled
did you? Believe me, shared memory wouldn't work at all if that was the
case.

This change is wrong. init_per_cpu() is called too early for the monarch.
disable_sr_hashing relies on the boot cpu data to be initialized to
determine which code should be used to disable the sr hashing.  It might
work for PA2.0, since it is the default case, but you probably broke all
of the other processors.

disable_sr_hashing() is called for the monarch in mm/init.c in
setup_bootmem().

John Marvin
jsm@fc.hp.com

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

On Sat, Feb 08, 2003 at 11:23:03PM +0000, Matthew Wilcox wrote:
> Is all that's needed to take the latest binutils from debian unstable
> and rebuild it on woody?

I've rebuilt "unstable" binutils + ldwa,o patch on "testing" and dropped
them on
	ftp://ftp.parisc-linux.org/unofficial-debs/

-rw-r--r--    1 grundler ftpadmin   478700 Feb  8 23:51 binutils-dev_2.13.90.0.16-1_hppa.deb
-rw-r--r--    1 grundler ftpadmin  3311272 Feb  8 23:53 binutils-multiarch_2.13.90.0.16-1_hppa.deb
-rw-r--r--    1 grundler ftpadmin  2307548 Feb  8 23:54 binutils_2.13.90.0.16-1_hppa.deb

They install fine on my c3k though TBH, I haven't tried to use them.
(I did use the tarballs before posting earlier).
If someone wants to repeat that exercise for woody, that would be
fine with me.

/me checks off an item from his TODO list

Apperently, we still have problems with timers or timer code on PA20 SMP.
Still haven't been able to isolate this to any peice of code. :^(

g'night,
grant

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

On Sun, Feb 09, 2003 at 12:40:14AM -0700, John Marvin wrote:
> > o moved disable_sr_hash() from SMP to common code path so all
> > CPU's (including monarch) have this disabled.
> 
> Huh? You didn't seriously think the monarch still had sr hashing enabled
> did you?

sorry - I did.
I could not find where it was getting cleared for the monarch.

> Believe me, shared memory wouldn't work at all if that was the case.

ok.

> This change is wrong. init_per_cpu() is called too early for the monarch.

yup - it's before collect_boot_cpu_data(). :^(

> disable_sr_hashing() is called for the monarch in mm/init.c in
> setup_bootmem().

ugh. my bad.
I was only looking in arch/parisc/kernel/ since that's where it's defined
and was being used in the SMP case.

Can I move the disable_sr_hashing() call from setup_bootmem() to
before/after cache_init() in setup_arch()?

Please feel free to correct if you have time to muck with it.
If my damage is not backed out in the morning, I'll back it out then.

thanks for pointing out this stupidity,
grant

[parisc-linux] re: [parisc-linux-cvs] linux grundler

[John Marvin]

> Can I move the disable_sr_hashing() call from setup_bootmem() to
> before/after cache_init() in setup_arch()?

Sure. As long as you call it before paging_init() you will be OK.

> Please feel free to correct if you have time to muck with it.
> If my damage is not backed out in the morning, I'll back it out then.

I don't have a current tree and I need to go to bed.

John

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Matthew Wilcox]

On Sun, Feb 09, 2003 at 01:11:21AM -0700, Grant Grundler wrote:
> I've rebuilt "unstable" binutils + ldwa,o patch on "testing" and dropped
> them on
> 	ftp://ftp.parisc-linux.org/unofficial-debs/
> 
> -rw-r--r--    1 grundler ftpadmin   478700 Feb  8 23:51 binutils-dev_2.13.90.0.16-1_hppa.deb
> -rw-r--r--    1 grundler ftpadmin  3311272 Feb  8 23:53 binutils-multiarch_2.13.90.0.16-1_hppa.deb
> -rw-r--r--    1 grundler ftpadmin  2307548 Feb  8 23:54 binutils_2.13.90.0.16-1_hppa.deb

I've removed these.  Few problems:

 - Same version number as the unstable package, so an upgrade wouldn't
   replace them
 - Not listed in the Packages file.
 - debian/changelog not updated

I'm doing a fresh build now.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Matthew Wilcox]

On Sat, Feb 08, 2003 at 08:10:14PM -0700, Grant Grundler wrote:
> Just drop that in debian/patches before building the debs.
> That patch applies clean to the binutils for unstable.
> I don't even pretend to understand how to properly build
> debian packages, much less binutils or "cross release" builds.
> That's why I made the tarball for "testing".

OK.  It's not really hard, but I don't mind doing it.  It's not like
this is a regular occurrence.  It's building now; when I've finished
I'll upload it to unofficial-debs and people will be able to apt-get
install it from there.

> I don't care to find out the hard way.
> I'd rather just comply with the architecture and not worry about it.
> If someone can demonstrate a perf advantage or issue, I'll be
> more receptive.

Sure.  When someone's trying to implement futexes, this may prove critical..

> > One final point.... up till now, we've been telling people it's OK to
> > run kernels configured for PA1.1 on PA2.0 processors.  This patch says
> > to me that's not safe.
> 
> Only for SMP. I think for UP the rule still holds.

Agree.  That was implicit in the kernel list i gave later, but I should've
stated it explicitly.

> Unfortunately yes.
> 
> OTOH, PA20 SMP still hasn't proven stable so maybe it's not worth
> doing at the moment either.  Once PA20 SMP is stable, we could drop
> the 64-bit UP kernels since most systems that *require* 64-bit are SMP.

Sure, but there's a measurable performance difference if you compile out
spinlocks

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Matthew Wilcox]

On Sun, Feb 09, 2003 at 12:29:13PM +0000, Matthew Wilcox wrote:
> OK.  It's not really hard, but I don't mind doing it.  It's not like
> this is a regular occurrence.  It's building now; when I've finished
> I'll upload it to unofficial-debs and people will be able to apt-get
> install it from there.

done.  http://ftp.parisc-linux.org/unofficial-debs/README
untested as i don't have root on any machine that's convenient.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[James Bottomley]

On Sat, 2003-02-08 at 20:03, Matthew Wilcox wrote:
> I think it's even worse than that.  What stops gcc reordering:
> 
> typedef struct {
>         spinlock_t lock;
>         volatile int counter;
> } rwlock_t;
> 
> static  __inline__ void _raw_read_lock(rwlock_t *rw)
> {
>         while (__ldcw (&(x)->lock) == 0) \
>                 while (((x)->lock) == 0) ; } while (0)
>         rw->counter++;
>         do { (x)->lock = 1; } while(0)
> }
> 
> to:
> 
>         while (__ldcw (&(x)->lock) == 0) \
>                 while (((x)->lock) == 0) ; } while (0)
>         do { (x)->lock = 1; } while(0)
>         rw->counter++;

Compilers themselves have fairly strong reordering rules.  For instance,
do { } while() blocks cannot be reordered like your example (that's why
the kernel uses do { } while(0); as a compiler reordering barrier.

You can if you prefer use the barrier() macro, which prevents the
compiler from reordering statements around it.

Of course, the processor can still reorder what the compiler doesn't as
part of its speculation and optimisation (that's what mb(), rmb() and
wmb() are all about).

James

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

On Sun, Feb 09, 2003 at 12:29:13PM +0000, Matthew Wilcox wrote:
> I'll upload it to unofficial-debs and people will be able to apt-get
> install it from there.

cool - thanks.

> Sure, but there's a measurable performance difference if you compile out
> spinlocks

if people care about the last 5% performance, they still have several
options:
o build your own kernel
o run HPUX

I've not done or seen any lmbench perf results recently but before hpux
was 10x faster on context switch/task related stuff.  And X11 server
takes advantage of HW acceleration.
(I'm associating UP systems with graphics which isn't always true)

grant

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Aaron St. Pierre]

In another life Grant Grundler wrote:

> On Sun, Feb 09, 2003 at 12:29:13PM +0000, Matthew Wilcox wrote:
> > I'll upload it to unofficial-debs and people will be able to apt-get
> > install it from there.
> 
> cool - thanks.
> 
> > Sure, but there's a measurable performance difference if you compile out
> > spinlocks
> 
> if people care about the last 5% performance, they still have several
> options:
> o build your own kernel

	As far as you know am I the only person, that has reported not being
	able to boot a 2.4.20-pa?? kernel compiled either natively or cross ? 

	By the way, I tried pa24 today, though I haven't built it natively
	yet I cross compiled it to no avail... 

> o run HPUX
> 
> I've not done or seen any lmbench perf results recently but before hpux
> was 10x faster on context switch/task related stuff.  And X11 server
> takes advantage of HW acceleration.
> (I'm associating UP systems with graphics which isn't always true)
> 
> grant
> _______________________________________________
> parisc-linux mailing list
> parisc-linux@lists.parisc-linux.org
> http://lists.parisc-linux.org/mailman/listinfo/parisc-linux

-- 
Aaron St. Pierre			tel: 978.828.6177
asp@ungod.com

 Either I'm dead or my watch has stopped.
 		-- Groucho Marx's last words

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Randolph Chung]

> I've not done or seen any lmbench perf results recently but before hpux

well, we can fix that... :) Here are the numbers for a 2x440Mhz A500 running 
2.4.20-pa24 SMP.

btw, if you look at
http://lists.parisc-linux.org/pipermail/parisc-linux/2002-April/015984.html
we are only 2-3x slower than hpux :-)

I'm a bit confused about the "mmap latency" numbers. why are they so
high?

Related to this, thibaut and I were experimenting with running dbench on
two A500s today running identical kernels, but one is 2x440MHz and one
is 2x550MHz. The 550MHz is almost 10x faster. Is that expected?
Memory/disk configurations (3GB RAM in 440MHz, 2.5GB in 550MHz, etc) are 
not exactly the same, but I wouldn't have expected them to differ by that much.

randolph

                 L M B E N C H  2 . 0   S U M M A R Y
                 ------------------------------------


Basic system parameters
----------------------------------------------------
Host                 OS Description              Mhz
                                                    
--------- ------------- ----------------------- ----
ios       Linux 2.4.20-        hppa64-linux-gnu  440

Processor, Processes - times in microseconds - smaller is better
----------------------------------------------------------------
Host                 OS  Mhz null null      open selct sig  sig  fork exec sh  
                             call  I/O stat clos TCP   inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ----- ---- ---- ---- ---- ----
ios       Linux 2.4.20-  440 0.73 1.85 10.2 11.8 110.8 2.17 16.9 17.K 41.K 85.K

Context switching - times in microseconds - smaller is better
-------------------------------------------------------------
Host                 OS 2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
                        ctxsw  ctxsw  ctxsw ctxsw  ctxsw   ctxsw   ctxsw
--------- ------------- ----- ------ ------ ------ ------ ------- -------
ios       Linux 2.4.20- 5.630 5.1500 4.9900 9.0800   23.4    52.1   175.8

*Local* Communication latencies in microseconds - smaller is better
-------------------------------------------------------------------
Host                 OS 2p/0K  Pipe AF     UDP  RPC/   TCP  RPC/ TCP
                        ctxsw       UNIX         UDP         TCP conn
--------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
ios       Linux 2.4.20- 5.630  20.4 48.4  89.2 172.5 114.1 351.5 1000

File & VM system latencies in microseconds - smaller is better
--------------------------------------------------------------
Host                 OS   0K File      10K File      Mmap    Prot    Page	
                        Create Delete Create Delete  Latency Fault   Fault 
--------- ------------- ------ ------ ------ ------  ------- -----   ----- 
ios       Linux 2.4.20-  130.0   80.0  509.9  180.0  3120.0K 603.4    58.0

*Local* Communication bandwidths in MB/s - bigger is better
-----------------------------------------------------------
Host                OS  Pipe AF    TCP  File   Mmap  Bcopy  Bcopy  Mem   Mem
                             UNIX      reread reread (libc) (hand) read write
--------- ------------- ---- ---- ---- ------ ------ ------ ------ ---- -----
ios       Linux 2.4.20- 49.1 81.0 33.6   74.0  268.4  201.8  168.8 260. 250.9

Memory latencies in nanoseconds - smaller is better
    (WARNING - may not be correct, check graphs)
---------------------------------------------------
Host                 OS   Mhz  L1 $   L2 $    Main mem    Guesses
--------- -------------  ---- ----- ------    --------    -------
ios       Linux 2.4.20-   440  20.0   20.0  220.0    No L1 cache?

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[John Marvin]

> 2.4.20-pa24 PA20 memory ordering
> Kudos to John David Anglin and Carlos O'Donnell for realizing
> PA 2.0 is not strongly ordered like PA1.x is.
> Read appendix G or PA-RISC 2.0 Architecture (Gerry Kane) for
> details on "Memory Ordering Model".

Sorry, this is wrong.  I'm afraid you are wasting your time with all of
these code changes.

The problem is that the Kane book defines the architecture, i.e. it
defines what can be done, not what has been done.  Of course, to know what
has been done you have to read the various processor ERS's, and I'm not
sure we've made any of the PA2.0 chip ERS's available.

Anyway, no PA2.0 processor has implemented the PSW O bit, TLB O bit or
support for the ,o completers (they are just ignored).  All of the PA2.0
processors are strongly ordered, just like the PA1.x processors are.  I
can pretty much guarantee that no future PA processor is going to change
that fact.

John Marvin
jsm@fc.hp.com

Re: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Grant Grundler]

On Sun, Feb 09, 2003 at 04:24:54PM -0500, Aaron St. Pierre wrote:
> In another life Grant Grundler wrote:
> > if people care about the last 5% performance, they still have several
> > options:
> > o build your own kernel
> 
> 	As far as you know am I the only person, that has reported not being
> 	able to boot a 2.4.20-pa?? kernel compiled either natively or cross ? 

yes. So it's not an option for you.

> > o run HPUX
> > 
> > I've not done or seen any lmbench perf results recently but before hpux
> > was 10x faster on context switch/task related stuff.  And X11 server

Seems I remembered this partially wrong.
Linux was slightly faster in lots of areas, ~5x slower on fork/exec/shi,
and ~10x slower mmap latency.

http://lists.parisc-linux.org/pipermail/parisc-linux/2002-March/015966.html

grant

[parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Carlos O'Donell]

> Builds/links/boots using my c3000 .config.

Same here. Not dying under load either :)

c.

RE: [parisc-linux] Re: [parisc-linux-cvs] linux grundler

[Joel Soete]

>>
>>> Builds/links/boots using my c3000 .config.
>
>Same here. Not dying under load either :)
>
>c.

hmm i tested successfully NS87... builtin but failed as module:
modprob do a page fault and lsmod shows me a module 'busy' and so the system

ailled to reboot (only power off button works but fs were so not cleanly
umount :( )

Cheers,
    Joel




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