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From:   Vipin Sharma <vipinsh@google.com>
Date:   Fri, 14 Oct 2022 11:26:31 -0700
Message-ID: <CAHVum0d2Jfr=WVxKxvnmwGKzPfV3vN5dbz11=rdcW6qoSoobew@mail.gmail.com>
Subject: Re: [PATCH v5 0/5] dirty_log_perf_test vCPU pinning
To:     Sean Christopherson <seanjc@google.com>,
        "Wang, Wei W" <wei.w.wang@intel.com>
Cc:     David Matlack <dmatlack@google.com>,
        "andrew.jones@linux.dev" <andrew.jones@linux.dev>,
        "pbonzini@redhat.com" <pbonzini@redhat.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Fri, Oct 14, 2022 at 9:55 AM David Matlack <dmatlack@google.com> wrote:
>
> On Fri, Oct 14, 2022 at 9:34 AM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Fri, Oct 14, 2022, Wang, Wei W wrote:
> > > On Tuesday, October 11, 2022 6:06 AM, Vipin Sharma wrote:
> > > > Pin vCPUs to a host physical CPUs (pCPUs) in dirty_log_perf_test and optionally
> > > > pin the main application thread to a physical cpu if provided. All tests based on
> > > > perf_test_util framework can take advantage of it if needed.
> > > >
> > > > While at it, I changed atoi() to atoi_paranoid(), atoi_positive,
> > > > atoi_non_negative() in other tests, sorted command line options alphabetically
> > > > in dirty_log_perf_test, and added break between -e and -g which was missed in
> > > > original commit when -e was introduced.
> > >
> > > Just curious why not re-using the existing tools (e.g. taskset) to do the pinning?
> >
> > IIUC, you're suggesting the test give tasks meaningful names so that the user can
> > do taskset on the appropriate tasks?  The goal is to ensure vCPUs are pinned before
> > they do any meaningful work.  I don't see how that can be accomplished with taskset
> > without some form of hook in the test to effectively pause the test until the user
> > (or some run script) is ready to continue.
>
> A taskset approach would also be more difficult to incorporate into
> automated runs of dirty_log_perf_test.
>
> >
> > Pinning aside, naming the threads is a great idea!  That would definitely help
> > debug, e.g. if one vCPU gets stuck or is lagging behind.
>
> +1

I also like the idea.

Sean:
Do you want a v6 with the naming patch or you will be fine taking v5,
if there are no changes needed in v5, and I can send a separate patch
for naming?