From: Peter Zijlstra <peterz@infradead.org>
To: Song Liu <songliubraving@fb.com>
Cc: bpf <bpf@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"acme@kernel.org" <acme@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"kjain@linux.ibm.com" <kjain@linux.ibm.com>,
Kernel Team <Kernel-team@fb.com>
Subject: Re: [PATCH v5 bpf-next 1/3] perf: enable branch record for software events
Date: Sat, 4 Sep 2021 12:18:34 +0200 [thread overview]
Message-ID: <20210904101834.GC4323@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <6BA620C1-D311-4992-8119-68A740ABA8BC@fb.com>
On Fri, Sep 03, 2021 at 04:45:29PM +0000, Song Liu wrote:
> Hi Peter,
>
> > On Sep 3, 2021, at 1:27 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Thu, Sep 02, 2021 at 09:57:04AM -0700, Song Liu wrote:
> >
> >> +static int
> >> +intel_pmu_snapshot_branch_stack(struct perf_branch_entry *entries, unsigned int cnt)
> >> +{
> >> + struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
> >> +
> >> + intel_pmu_disable_all();
> >> + intel_pmu_lbr_read();
> >> + cnt = min_t(unsigned int, cnt, x86_pmu.lbr_nr);
> >> +
> >> + memcpy(entries, cpuc->lbr_entries, sizeof(struct perf_branch_entry) * cnt);
> >> + intel_pmu_enable_all(0);
> >> + return cnt;
> >> +}
> >
> > Given this disables the PMI from 'random' contexts, should we not add
> > IRQ disabling around this to avoid really bad behaviour?
>
> Do you mean we should add (instead of not add) IRQ disable?
Yeah, I tihnk we want local_irq_save()/restore() here.
next prev parent reply other threads:[~2021-09-04 10:19 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-02 16:57 [PATCH v5 bpf-next 0/3] bpf: introduce bpf_get_branch_snapshot Song Liu
2021-09-02 16:57 ` [PATCH v5 bpf-next 1/3] perf: enable branch record for software events Song Liu
2021-09-02 20:49 ` John Fastabend
2021-09-03 8:02 ` Peter Zijlstra
2021-09-03 16:50 ` Song Liu
2021-09-07 18:59 ` Song Liu
2021-09-07 20:50 ` Andrii Nakryiko
2021-09-03 8:27 ` Peter Zijlstra
2021-09-03 16:45 ` Song Liu
2021-09-04 10:18 ` Peter Zijlstra [this message]
2021-09-02 16:57 ` [PATCH v5 bpf-next 2/3] bpf: introduce helper bpf_get_branch_snapshot Song Liu
2021-09-02 20:56 ` John Fastabend
2021-09-02 22:04 ` Song Liu
2021-09-02 22:53 ` Andrii Nakryiko
2021-09-02 23:03 ` Song Liu
2021-09-02 23:05 ` Andrii Nakryiko
2021-09-03 1:03 ` Alexei Starovoitov
2021-09-03 8:28 ` Peter Zijlstra
2021-09-03 16:58 ` Song Liu
2021-09-03 8:47 ` Peter Zijlstra
2021-09-03 17:06 ` Song Liu
2021-09-03 17:10 ` Andrii Nakryiko
2021-09-04 10:24 ` Peter Zijlstra
2021-09-04 10:55 ` Peter Zijlstra
2021-09-02 16:57 ` [PATCH v5 bpf-next 3/3] selftests/bpf: add test for bpf_get_branch_snapshot Song Liu
2021-09-02 21:05 ` John Fastabend
2021-09-02 22:54 ` [PATCH v5 bpf-next 0/3] bpf: introduce bpf_get_branch_snapshot Andrii Nakryiko
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210904101834.GC4323@worktop.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=Kernel-team@fb.com \
--cc=acme@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=kjain@linux.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=songliubraving@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.