On 2011-04-25 20:35, Aurelien Jarno wrote: > On Thu, Apr 14, 2011 at 09:14:35AM +0200, Jan Kiszka wrote: >> On 2011-04-13 22:16, Aurelien Jarno wrote: >>> On Mon, Apr 11, 2011 at 10:27:41PM +0200, Jan Kiszka wrote: >>>> These patches were posted before. They bring down the overhead of the >>>> io-thread mode for TCG here, specifically when emulating SMP. >>>> >>>> The major change in this version, besides rebasing, is the exclusion of >>>> KVM from the main loop polling optimization. >>>> >>>> >>>> >>>> Jan Kiszka (3): >>>> Do not drop global mutex for polled main loop runs >>>> Poll main loop after I/O events were received >>>> Do not kick vcpus in TCG mode >>>> >>>> cpus.c | 2 +- >>>> sysemu.h | 2 +- >>>> vl.c | 22 ++++++++++++++++------ >>>> 3 files changed, 18 insertions(+), 8 deletions(-) >>>> >>> >>> Thanks for working on improving the io-thread with TCG. Your patches >>> make sense, but they don't seems to fix the slowdown observed when >>> enabling the io-thread. Well maybe they were not supposed to. This is >>> for example the results of netperf between guest and host using virtio: >>> >>> no io-thread 122 MB/s >>> io-thread 97 MB/s >>> io-thread + patches 98 MB/s >>> >> >> Can you capture ftraces of io-thread enabled & disabled runs? They just >> need to cover a hand full of frames. >> > > From what I have been able to get from the ftraces documentation, it's > possible multiple tracers. Which tracers would you like to use there? > The best would be a set of command lines to run.
Sorry, of course: Just download, build & install trace-cmd [1], then execute "trace-cmd record -b 16000 -e all" while qemu is running. The result is written to trace.dat in the current directory. Visualize it via "trace-cmd report" (or kernelshark if you built that as well). Jan [1] git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/trace-cmd.git
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