Re: [2.4.17/18pre] VM and swap - it's really unusable

Ken Brownfield
2002-01-03T20:23:24Z

Unfortunately, I lost the response that basically said "2.4 looks stable
to me", but let me count the ways in which I agree with Andreas'
sentiment:

A) VM has major issues
1) about a dozen recent OOPS reports in VM code
2) VM falls down on large-memory machines with a
high inode count (slocate/updatedb, i/dcache)
3) Memory allocation failures and OOM triggers
even though caches remain full.
4) Other bugs fixed in -aa and others
B) Live- and dead-locks that I'm seeing on all 2.4 production
machines > 2.4.9, possibly related to A. But how will I
ever find out?
C) IO-APIC code that requires noapic on any and all SMP
machines that I've ever run on.

I don't have anything against anyone here -- I think everyone is doing a
fine job. It's an issue of acceptance of the problem and focus. These
issues are all showstoppers for me, and while I don't represent the 90%
of the Linux market that is UP desktops, IMHO future work on the kernel
will be degraded by basic functionality that continues to cause
problems.

I think seeing some of Andrea's and Andrew's et al patches actually
*happen* would be a good thing, since 2.4 kernels are decidedly not
ready for production here. I am forced to apply 26 distinct patch sets
to my kernels, and I am NOT the right person to make these judgements.
Which is why I was interested in an LKML summary source, though I
haven't yet had a chance to catch up on that thread of comment.

Having a glitch in the radeon driver is one thing; having persistent,
fatal, and reproducable failures in universal kernel code is entirely
another.

--
Ken.
brownfld@irridia.com

On Fri, Dec 28, 2001 at 09:16:38PM +0100, Andreas Hartmann wrote:
| Hello all,
|
| Again, I did a rsync-operation as described in
| "[2.4.17rc1] Swapping" MID <3C1F4014.2010705@athlon.maya.org>.
|
| This time, the kernel had a swappartition which was about 200MB. As the
| swap-partition was fully used, the kernel killed all processes of knode.
| Nearly 50% of RAM had been used for buffers at this moment. Why is there
| so much memory used for buffers?
|
| I know I repeat it, but please:
|
| Fix the VM-management in kernel 2.4.x. It's unusable. Believe
| me! As comparison: kernel 2.2.19 didn't need nearly any swap for
| the same operation!
|
| Please consider that I'm using 512 MB of RAM. This should, or better:
| must be enough to do the rsync-operation nearly without any swapping -
| kernel 2.2.19 does it!
|
| The performance of kernel 2.4.18pre1 is very poor, which is no surprise,
| because the machine swaps nearly nonstop.
|
|
| Regards,
| Andreas Hartmann
|
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