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Re: [Qemu-devel] [PATCH] Huge TLB performance improvement
From: |
Thiemo Seufer |
Subject: |
Re: [Qemu-devel] [PATCH] Huge TLB performance improvement |
Date: |
Sun, 12 Nov 2006 13:52:57 +0000 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Laurent Desnogues wrote:
> Daniel Jacobowitz a écrit :
> >
> >Straight qemu with my previously posted MIPS patches takes 6:13 to
> >start and reboot a MIPS userspace (through init, so lots of fork/exec).
> >
> >Thiemo's patch, which flushes the whole jump buffer, cuts it to 1:40.
> >
> >A patch which finds the entries which need to be flushed more
> >efficiently cuts it to 1:21.
> >
> >A patch which flushes up to 1/32nd of the jump buffer indiscriminately
> >cuts it to 1:11-1:13.
>
> Warning: I don't know anything about the Qemu MMU implementation
> so this question is perhaps stupid :)
>
> Did you try to benchmark some user space applications with the
> various implementations you propose?
A "benchmark" I did was compiling lmbench, which became more than twice
as fast. I didn't bother to do real measurements.
> The boot of a Linux kernel
> is quite heavy on various kinds of flushes and so is very
> different from "standard" applications.
At least the MIPS kernel is indeed different in that it uses non-trivial
TLB mappings nearly excusively for modules and userland. IOW, the
kernel-side MMU overhead at boot time is neglectable. My patch made no
significant difference for that case.
Thiemo
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/05
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/11
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Laurent Desnogues, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement,
Thiemo Seufer <=
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Paul Brook, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Thiemo Seufer, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Paul Brook, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Thiemo Seufer, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Dirk Behme, 2006/11/12
- Re: [Qemu-devel] [PATCH] Huge TLB performance improvement, Daniel Jacobowitz, 2006/11/12