From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Aurelien Jarno <aurelien-rXXEIb44qovR7s880joybQ@public.gmane.org>
Cc: kvm-devel <kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
Subject: Re: [ANNOUNCE] kvm-14 release
Date: Wed, 21 Feb 2007 10:06:06 +0200 [thread overview]
Message-ID: <45DBFD6E.2060507@qumranet.com> (raw)
In-Reply-To: <45DB7514.3040409-rXXEIb44qovR7s880joybQ@public.gmane.org>
Aurelien Jarno wrote:
> Avi Kivity a écrit :
>
>> Aurelien Jarno wrote:
>>
>>> The bad news is that kvm-14 seems to be a lot slower than kvm-12 +
>>> modules from kernel 2.6.20. This is the case with a GNU/kFreeBSD guest.
>>> kvm-12 was about 1.5 time faster than qemu + kqemu. kvm-20 is slower
>>> than qemu without kqemu...
>>>
>>> Does anybody have an idea about this performance regression?
>>>
>>>
>> What is your workload? How are you measuring performance?
>>
>
> Sorry to answer only now, it took me some time to do some more
> measurements and have some numbers. I am simply building a Debian
> package (simulpic) and measuring the build time. Basically the command is:
>
> apt-get source simulpic
> cd simulpic-2005-1-28
> time debuild -uc us
>
> It surely not a performance index, but I guess it is ok to compare
> performances between version. It is also quite representative of my use
> of the machine.
>
Real workloads (likr this) are more important than synthetic benchmarks.
> The guest is Debian GNU/kFreeBSD amd64 (ie FreeBSD kernel + GNU libc).
> It is accessed via ssh, and kvm is started with -nographic, so there is
> no influence of xorg.
>
> I am doing my tests on an Athlon X2 3800+ machine, running a 2.6.20
> kernel. During all my tests, the machine is not loaded with other tasks
> (except systems tasks), so qemu or kvm have a full core available. Top
> shows that the core is used between 95 and 100% during the whole build
> in all cases.
>
> The tests I have made are presented below. In all cases I have verified
> that the real time correspond to the time of my wall clock, it is
> correct in all case given the resolution of my wall clock (1 s):
>
> qemu
> ----
> real 3m16.626s
> user 2m22.654s
> sys 0m41.738s
>
Is this qemu 0.8.2 or qemu 0.9.0?
> qemu + kqemu
> ------------
> real 0m51.529s
> user 0m11.775s
> sys 0m36.215s
>
> kvm 12 + modules from kernel 2.6.20
> -----------------------------------
> real 0m30.635s
> user 0m16.357s
> sys 0m8.511s
>
> kvm 12
> ------
> real 0m25.357s
> user 0m16.259s
> sys 0m6.496s
>
> kvm 13
> ------
> real 0m23.415s
> user 0m15.177s
> sys 0m5.811s
>
So far so good. Steady improvement. The low system time indicates a
lot of I/O and inefficiency in the qemu device emulation (guest time is
charged as system time).
> kvm 14
> ------
> real 7m47.310s
> user 5m17.359s
> sys 2m3.184s
>
>
> Using kvm 14, the system is clearly not responsive at all. You can see
> that without running a benchmark.
>
kvm-14 is mostly qemu 0.9.0. Do you get the same results with kvm-14
-no-kvm?
What is your disk image file format, or are you using a partition?
Do the results change (on kvm-14) if you pin the guest to a core with
'taskset 1 qemu ...'
Thank you for taking the time to do real measurements and report the
results clearly. That makes it possible (I hope) to find the cause and
fix it.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys-and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
next prev parent reply other threads:[~2007-02-21 8:06 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-19 11:01 [ANNOUNCE] kvm-14 release Avi Kivity
[not found] ` <45D98390.6060001-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-19 13:16 ` Daniel P. Berrange
[not found] ` <20070219131633.GF31525-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2007-02-19 13:21 ` Avi Kivity
[not found] ` <45D9A464.8040406-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-19 15:37 ` James Morris
2007-02-19 15:42 ` Avi Kivity
[not found] ` <45D9C57D.9030203-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-05 8:52 ` Avi Kivity
2007-02-20 1:06 ` Rusty Russell
[not found] ` <1171933567.8218.53.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2007-02-20 5:53 ` James Morris
2007-02-19 14:37 ` Andreas Hasenack
[not found] ` <200702191237.39291.ahasenack-y7mWNqJcIDpfJ/NunPodnw@public.gmane.org>
2007-02-19 14:46 ` Avi Kivity
2007-02-19 15:24 ` Omar Khan
[not found] ` <loom.20070219T161915-755-eS7Uydv5nfjZ+VzJOa5vwg@public.gmane.org>
2007-02-19 15:26 ` Avi Kivity
2007-02-19 22:34 ` Aurelien Jarno
[not found] ` <45DA25D9.1060509-rXXEIb44qovR7s880joybQ@public.gmane.org>
2007-02-20 7:15 ` Avi Kivity
[not found] ` <45DA9FFA.2020009-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-20 22:24 ` Aurelien Jarno
[not found] ` <45DB7514.3040409-rXXEIb44qovR7s880joybQ@public.gmane.org>
2007-02-21 8:06 ` Avi Kivity [this message]
[not found] ` <45DBFD6E.2060507-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-21 14:06 ` Aurelien Jarno
[not found] ` <45DC51E3.7010205-rXXEIb44qovR7s880joybQ@public.gmane.org>
2007-02-21 14:18 ` Avi Kivity
[not found] ` <45DC54B5.9080608-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-21 14:55 ` Laurent Vivier
[not found] ` <45DC5D4E.5000300-6ktuUTfB/bM@public.gmane.org>
2007-02-21 15:31 ` Anthony Liguori
[not found] ` <45DC65C9.6010104-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-02-21 16:07 ` Laurent Vivier
2007-02-22 16:35 ` Laurent Vivier
[not found] ` <45DDC641.3030001-6ktuUTfB/bM@public.gmane.org>
2007-02-22 16:38 ` Avi Kivity
[not found] ` <45DDC6F3.8080104-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-22 17:25 ` Anthony Liguori
[not found] ` <45DDD21F.4080202-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-02-22 17:29 ` Avi Kivity
[not found] ` <45DDD30D.4000809-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-22 18:12 ` Anthony Liguori
[not found] ` <45DDDD01.7030802-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
2007-02-28 14:12 ` Laurent Vivier
2007-02-26 15:43 ` Aurelien Jarno
[not found] ` <45E30037.90007-rXXEIb44qovR7s880joybQ@public.gmane.org>
2007-02-26 15:57 ` Laurent Vivier
[not found] ` <45E30354.3020407-6ktuUTfB/bM@public.gmane.org>
2007-02-26 16:23 ` Avi Kivity
[not found] ` <45E3097C.7020606-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-26 16:46 ` Laurent Vivier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=45DBFD6E.2060507@qumranet.com \
--to=avi-atkuwr5tajbwk0htik3j/w@public.gmane.org \
--cc=aurelien-rXXEIb44qovR7s880joybQ@public.gmane.org \
--cc=kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.