From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Blue Swirl <blauwirbel@gmail.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] target-sparc register window handling
Date: Tue, 09 Oct 2012 09:53:32 -0700 [thread overview]
Message-ID: <5074568C.20602@twiddle.net> (raw)
In-Reply-To: <20121008061747.GE4055@ohm.aurel32.net>
On 10/07/2012 11:17 PM, Aurelien Jarno wrote:
> For what it worth, I measure a 4% slow down booting a sparc64 guest on a
> Core-i5 2500 machine. I guess the memcpy() of the register windows is
> more expensive that the gain on the TCG side, though it should be
> probably be confirmed using some profiling tools.
Confirmed with userland testing (running cc1plus on large input),
and I see much more than 4% slow down -- more like 15%. I can reduce
this by adding save/restore window inc/dec optimization within the
cpu_set_cwp routine, but that only gets me back to 5% slow down.
A bit disappointing; I guess other avenues will want exploring.
Patch withdrawn.
r~
next prev parent reply other threads:[~2012-10-09 16:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-06 0:00 [Qemu-devel] [PATCH] target-sparc register window handling Richard Henderson
2012-10-06 0:00 ` [Qemu-devel] [PATCH] target-sparc: Use TCG registers for windowed registers Richard Henderson
2012-10-06 10:15 ` [Qemu-devel] [PATCH] target-sparc register window handling Aurelien Jarno
2012-10-08 6:17 ` Aurelien Jarno
2012-10-09 16:53 ` Richard Henderson [this message]
2012-10-09 17:06 ` Aurelien Jarno
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