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Re: [Qemu-devel] [PATCH 1/3] qsp: QEMU's Synchronization Profiler
From: |
Emilio G. Cota |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] qsp: QEMU's Synchronization Profiler |
Date: |
Wed, 15 Aug 2018 19:55:14 -0400 |
User-agent: |
Mutt/1.9.4 (2018-02-28) |
On Wed, Aug 15, 2018 at 00:53:23 -0400, Emilio G. Cota wrote:
> On Wed, Aug 15, 2018 at 11:09:42 +0800, Fam Zheng wrote:
> > On Mon, 08/13 13:11, Emilio G. Cota wrote:
> > > + --enable-sync-profiler) sync_profiler="yes"
> > > + ;;
> >
> > Curious, not asking for a change: can this be made a runtime option instead
> > of
> > compile time, since there's no library dependencies? That should make this
> > somewhat easier to use.
>
> Good point. I'll do some profiling tomorrow to see how the latency
> of the locking primitives could be minimized (ideally, not using
> the profiler should just add a well-predicted branch).
I reduced it to just a branch, but still, I measured a few percentage
points (1-2%, depending on the machine) slowdown when this is a
run-time option. (This is for a bootup+shutdown test of a guest.)
So I'll keep it as a build-time option, then.
Thanks,
Emilio
- Re: [Qemu-devel] [PATCH 2/3] monitor: show sync profiling info with 'info sync', (continued)
Re: [Qemu-devel] [PATCH 0/3] synchronization profiler, no-reply, 2018/08/15