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Re: [Qemu-devel] [PATCH 2/3] Get rid of temporary variable cache.
From: |
Paul Brook |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] Get rid of temporary variable cache. |
Date: |
Mon, 29 Jun 2009 19:34:55 +0100 |
On Monday 29 June 2009, Filip Navara wrote:
> The temporary variable cache actually hurts TCG more than it helps.
> Empirical results show that when running the Dhrystone benchmark with this
> patch improves the speed by about 2%.
I find it hard to believe this patch has any significant effect on runtime,
other than random variation. My guess is it spends almost all of its time in a
few guest loops, and no time doing translation. I'd expect the generated code
should be the same before and after.
I'm not saying this patch is a bad idea (new_tmp/dead_tmp predate
tcg_temp_free and are now redundant), just that I don't believe your benchmark
results.
Paul