Re: [PATCH RESEND 2/2] memory: Add tracepoint for dirty sync

[Peter Xu]

On Tue, Aug 17, 2021 at 09:25:56AM +0200, David Hildenbrand wrote:
> On 17.08.21 03:37, Peter Xu wrote:
> > Trace at memory_region_sync_dirty_bitmap() for log_sync() or 
> > global_log_sync()
> > on memory regions.  One trace line should suffice when it finishes, so as to
> > estimate the time used for each log sync process.
> 
> I wonder if a start/finish would be even nicer. At least it wouldn't really
> result in significantly more code changes :)

Note that the "name"s I added is not only for not using start/end, it's about
knowing which memory listener is slow.  Start/end won't achieve that if we
don't have a name for them.  So far I just wanted to identify majorly kvm,
vhost and kvm-smram, however it'll always be good when some log_sync is missed
when tracing.

I'm also wondering whether kvm-smram needs a whole bitmap as I don't know what
RAM would be touched within system manager mode (as I thought it should only
touch a very limited range and should be defined somewhere), but that's
off-topic.

If we want to make it start/end pair, I can do that too.  But the 1st patch
will still be wanted.

Thanks,

-- 
Peter Xu