From: "Matthew Kent" <mkent@magoazul.com>
To: Luca Tettamanti <kronos.it@gmail.com>
Cc: kvm-devel@lists.sourceforge.net,
Dan Kenigsberg <dank@qumranet.com>,
qemu-devel@nongnu.org
Subject: [Qemu-devel] Re: [kvm-devel] [PATCH/RFC 4/4] Add support for dynamic ticks.
Date: Fri, 17 Aug 2007 00:16:09 -0700 (PDT) [thread overview]
Message-ID: <42755.207.81.93.54.1187334969.squirrel@mail.voxel.net> (raw)
In-Reply-To: <1187296877557-git-send-email-kronos.it@gmail.com>
> If DYNAMIC_TICKS is defined qemu does not attepmt to generate SIGALRM at a
> constant rate. Rather, the system timer is set to generate SIGALRM only
> when it is needed. DYNAMIC_TICKS reduces the number of SIGALRMs sent to
> idle dynamic-ticked guests.
> Original patch from Dan Kenigsberg <dank@qumranet.com>
>
> Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Wow, this patch sure made a difference for some timings I've been doing
with kvm-35 and hackbench. All tests using 2.6.23-rc3+hrtimers patch for
x86_64/i386 tickless and a quad core intel:
[mkent@localhost ~]$ time ./hackbench 50
x86_64 host : real 0m10.845s
x86_64 host, bound to 1 cpu : real 0m21.884s
i386 guest+unix clock : real 0m49.206s
i386 guest+hpet clock : real 0m48.292s
i386 guest+dynticks clock : real 0m28.835s
Results are repeatable and verfied with a stopwatch because I didn't
believe them at first :)
Great stuff.
--
Matthew Kent <mkent@magoazul.com>
http://magoazul.com
next prev parent reply other threads:[~2007-08-17 7:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-16 20:41 [Qemu-devel] [PATCH/RFC 0/4] Rework alarm timer infrastrucure Luca Tettamanti
2007-08-16 20:41 ` [Qemu-devel] [PATCH/RFC 1/4] " Luca Tettamanti
2007-08-16 20:41 ` [Qemu-devel] [PATCH/RFC 2/4] Add -clock option Luca Tettamanti
2007-08-16 20:41 ` [Qemu-devel] [PATCH/RFC 3/4] Add support for HPET periodic timer Luca Tettamanti
2007-08-16 20:41 ` [Qemu-devel] [PATCH/RFC 4/4] Add support for dynamic ticks Luca Tettamanti
2007-08-17 7:16 ` Matthew Kent [this message]
2007-08-19 8:08 ` [Qemu-devel] Re: [kvm-devel] " Avi Kivity
2007-08-17 12:44 ` [Qemu-devel] Re: [kvm-devel] [PATCH/RFC 0/4] Rework alarm timer infrastrucure Avi Kivity
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