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

[David Hildenbrand <david@redhat.com>]

On 17.08.21 18:05, Peter Xu wrote:
> 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.

Yeah, absolutely, not complaining about the name, it will be valuable to 
have!


-- 
Thanks,

David / dhildenb