Re: [Qemu-devel] Re: [PATCH] upgraded mmap patches

[Magnus Damm <magnus.damm@gmail.com>]

On Sun, 09 Jan 2005 21:39:42 +0500, Alexander E. Patrakov
<patrakov@ums.usu.ru> wrote:
> Magnus Damm wrote:
> 
> > Hi All,
> >
> > I have just finished upgrading the CONFIG_MMU_MAP (aka mmap) patches
> > written by Piotrek. I have only tested to build the code with
> > --target-list=i386-softmmu and only on x86 hosts running Linux. I am
> > able to run Win XP SP2 as guest both with and without mmap
> > acceleration with the patch.
> >
> > The changes are not many since the last release by Piotrek, I just
> > made sure the code applied to CVS of today and yeah, I added some
> > basic code to support quad-word memory access. It is totally untested
> > and probably broken right now. Someone please look at part4 of the
> > patch and verify that I read 32-bit words the right way.
> >
> > Sorry PowerPC folks, no ppc host support yet. I will port up the ppc
> > host patches after someone has fixed so ppc compiles cleanly...
> >
> > The first three parts are simply upgraded versions of the files
> > v1-part[1-3].patch.gz that Piotrek posted to the list around a month
> > ago. Part4 contains changes by me.
> >
> > Enjoy, please report back to the list with problems and benchmarks!
> 
> Is a new patched qemu really supposed to be much slower than the original in
> the case when /proc/sys/vm/max_map_count doesn't contain a number that's
> big enough to enable acceleration?

I don't think so. I believe that the code should just fall back on the
ordinary softmmu implementation in that case. But I do not know the
code very well.

Did you experience the same effect with the old version of the patches?

Thanks.

/ magnus