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Date: Tue, 25 Aug 2020 15:54:37 +0800 From: "Jin, Yao" <yao.jin@...ux.intel.com> To: Like Xu <like.xu@...ux.intel.com>, Arnaldo Carvalho de Melo <acme@...nel.org> Cc: jolsa@...nel.org, peterz@...radead.org, mingo@...hat.com, alexander.shishkin@...ux.intel.com, Linux-kernel@...r.kernel.org, ak@...ux.intel.com, kan.liang@...el.com, yao.jin@...el.com Subject: Re: [PATCH v3] perf parse-events: Set exclude_guest=1 for user-space counting Hi Arnaldo, On 8/19/2020 11:05 AM, Like Xu wrote: > Hi Arnaldo, > > On 2020/8/17 10:32, Jin, Yao wrote: >> Hi Arnaldo, >> >> On 8/14/2020 8:47 PM, Arnaldo Carvalho de Melo wrote: >>> Em Fri, Aug 14, 2020 at 09:21:20AM +0800, Jin Yao escreveu: >>>> Currently if we run 'perf record -e cycles:u', exclude_guest=0. >>>> >>>> But it doesn't make sense in most cases that we request for >>>> user-space counting but we also get the guest report. >>>> >>>> Of course, we also need to consider perf kvm usage case that >>>> authorized perf users on the host may only want to count guest >>>> user space events. For example, >>>> >>>> perf kvm --guest record -e cycles:u >>> Ok, probably this works, but what if I want to record guest user samples >>> without using 'perf kvm'? >>> >>> Can we have a 'U' modifier, perhaps, for that? >>> >>> I.e. >>> >>> perf record -e cycles:uU would not set exclude_host not exclude_guest, >>> cycles:u excludes guest user, cycles:U excludes host user, would that be >>> possible? >>> >>> Anyway, I think that with what we have, your patch makes sense, having a >>> way to, without using 'perf kvm' still be able to sample the guest can >>> be done on top. of this. >>> >>> Xu, can we get your Reviewed-by if this addresses your concerns? > > My concern is about do not break the perf kvm usages and Yao did it in v3. > > Tested-by: Like Xu <like.xu@...ux.intel.com> > Can this patch be accepted? >>> >>> - Arnaldo >> >> Do you suggest we will create a new modifier 'U' as a follow-up patch? >> >> cycles:u - Count host user space but it doesn't count the guest user space (exclude_host = 0, >> exclude_guest = 1, exclude_kernel = 1, exclude_user = 0, exclude_hv = 1) >> >> cycles:U - Count the guest user space but it doesn't count the host user space (exclude_host = 1, >> exclude_guest = 0, exclude_kernel = 1, exclude_user = 0, exclude_hv = 1) >> >> Is above understanding correct? > > Do we really need to support sample guests without using perf kvm? > > If it's true, I would prefer "cycles:uG" to cover guest user space > events only, "cycles:kG" to cover guest kernel space events only, > and only host events are sampled without the ":G" modifier by default. > > I am not sure if ":G" has been used in perf. > That may be another good idea I think. :) Thanks Jin Yao > At the very least, this v3 patch may not > block the follow-up patch from Yao (if any). > > Thanks, > Like Xu > >> >> Thanks >> Jin Yao >
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