From: Mark Rutland <mark.rutland@arm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, will@kernel.org,
catalin.marinas@arm.com, Mark Brown <broonie@kernel.org>,
James Clark <james.clark@arm.com>, Rob Herring <robh@kernel.org>,
Marc Zyngier <maz@kernel.org>,
Suzuki Poulose <suzuki.poulose@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
linux-perf-users@vger.kernel.org
Subject: Re: [PATCH V11 05/10] arm64/perf: Add branch stack support in ARMV8 PMU
Date: Tue, 6 Jun 2023 11:41:17 +0100 [thread overview]
Message-ID: <ZH8NTSYMS4n2/edR@FVFF77S0Q05N.cambridge.arm.com> (raw)
In-Reply-To: <ba396c30-6719-1dfb-77c2-9f7e1715b57c@arm.com>
On Tue, Jun 06, 2023 at 04:04:25PM +0530, Anshuman Khandual wrote:
> On 6/5/23 17:35, Mark Rutland wrote:
> > On Wed, May 31, 2023 at 09:34:23AM +0530, Anshuman Khandual wrote:
> >> static int armv8pmu_probe_pmu(struct arm_pmu *cpu_pmu)
> >> @@ -1145,12 +1162,24 @@ static int armv8pmu_probe_pmu(struct arm_pmu *cpu_pmu)
> >> };
> >> int ret;
> >>
> >> + ret = armv8pmu_private_alloc(cpu_pmu);
> >> + if (ret)
> >> + return ret;
> >> +
> >> ret = smp_call_function_any(&cpu_pmu->supported_cpus,
> >> __armv8pmu_probe_pmu,
> >> &probe, 1);
> >> if (ret)
> >> return ret;
> >>
> >> + if (arm_pmu_branch_stack_supported(cpu_pmu)) {
> >> + ret = branch_records_alloc(cpu_pmu);
> >> + if (ret)
> >> + return ret;
> >> + } else {
> >> + armv8pmu_private_free(cpu_pmu);
> >> + }
> >
> > I see from the next patch that "private" is four ints, so please just add that
> > to struct arm_pmu under an ifdef CONFIG_ARM64_BRBE. That'll simplify this, and
> > if we end up needing more space in future we can consider factoring it out.
>
> struct arm_pmu {
> ........................................
> /* Implementation specific attributes */
> void *private;
> }
>
> private pointer here creates an abstraction for given pmu implementation
> to hide attribute details without making it known to core arm pmu layer.
> Although adding ifdef CONFIG_ARM64_BRBE solves the problem as mentioned
> above, it does break that abstraction. Currently arm_pmu layer is aware
> about 'branch records' but not about BRBE in particular which the driver
> adds later on. I suggest we should not break that abstraction.
I understand the rationale, but I think it's simpler for now to break that
abstraction. We can always refactor it later.
> Instead a global 'static struct brbe_hw_attr' in drivers/perf/arm_brbe.c
> can be initialized into arm_pmu->private during armv8pmu_branch_probe(),
> which will also solve the allocation-free problem.
IIUC that's not going to work for big.LITTLE systems where the BRBE support
varies, as we need this data per arm_pmu.
> Also similar helpers armv8pmu_task_ctx_alloc()/free() could be defined to
> manage task context cache i.e arm_pmu->pmu.task_ctx_cache independently.
>
> But now armv8pmu_task_ctx_alloc() can be called after pmu probe confirms
> to have arm_pmu->has_branch_stack.
I think those are different, and should be kept.
Thanks,
Mark.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-06-06 10:41 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-31 4:04 [PATCH V11 00/10] arm64/perf: Enable branch stack sampling Anshuman Khandual
2023-05-31 4:04 ` [PATCH V11 01/10] drivers: perf: arm_pmu: Add new sched_task() callback Anshuman Khandual
2023-06-05 7:26 ` Mark Rutland
2023-05-31 4:04 ` [PATCH V11 02/10] arm64/perf: Add BRBE registers and fields Anshuman Khandual
2023-06-05 7:55 ` Mark Rutland
2023-06-06 4:27 ` Anshuman Khandual
2023-06-13 16:27 ` Mark Rutland
2023-06-14 2:59 ` Anshuman Khandual
2023-05-31 4:04 ` [PATCH V11 03/10] arm64/perf: Add branch stack support in struct arm_pmu Anshuman Khandual
2023-06-05 7:58 ` Mark Rutland
2023-06-06 4:47 ` Anshuman Khandual
2023-05-31 4:04 ` [PATCH V11 04/10] arm64/perf: Add branch stack support in struct pmu_hw_events Anshuman Khandual
2023-06-05 8:00 ` Mark Rutland
2023-05-31 4:04 ` [PATCH V11 05/10] arm64/perf: Add branch stack support in ARMV8 PMU Anshuman Khandual
2023-06-02 2:33 ` Namhyung Kim
2023-06-05 2:43 ` Anshuman Khandual
2023-06-05 12:05 ` Mark Rutland
2023-06-06 10:34 ` Anshuman Khandual
2023-06-06 10:41 ` Mark Rutland [this message]
2023-06-08 10:13 ` Suzuki K Poulose
2023-06-09 4:00 ` Anshuman Khandual
2023-06-09 9:54 ` Suzuki K Poulose
2023-06-09 7:14 ` Anshuman Khandual
2023-05-31 4:04 ` [PATCH V11 06/10] arm64/perf: Enable branch stack events via FEAT_BRBE Anshuman Khandual
2023-06-02 1:45 ` Namhyung Kim
2023-06-05 3:00 ` Anshuman Khandual
2023-06-05 13:43 ` Mark Rutland
2023-06-09 4:30 ` Anshuman Khandual
2023-06-09 12:37 ` Mark Rutland
2023-06-09 4:47 ` Anshuman Khandual
2023-06-09 12:42 ` Mark Rutland
2023-06-09 5:22 ` Anshuman Khandual
2023-06-09 12:47 ` Mark Rutland
2023-06-09 13:15 ` Mark Rutland
2023-06-09 13:34 ` James Clark
2023-05-31 4:04 ` [PATCH V11 07/10] arm64/perf: Add PERF_ATTACH_TASK_DATA to events with has_branch_stack() Anshuman Khandual
2023-05-31 4:04 ` [PATCH V11 08/10] arm64/perf: Add struct brbe_regset helper functions Anshuman Khandual
2023-06-02 2:40 ` Namhyung Kim
2023-06-05 3:14 ` Anshuman Khandual
2023-06-05 23:49 ` Namhyung Kim
2023-06-13 17:17 ` Mark Rutland
2023-06-14 5:14 ` Anshuman Khandual
2023-06-14 10:59 ` Mark Rutland
2023-05-31 4:04 ` [PATCH V11 09/10] arm64/perf: Implement branch records save on task sched out Anshuman Khandual
2023-05-31 4:04 ` [PATCH V11 10/10] arm64/perf: Implement branch records save on PMU IRQ Anshuman Khandual
2023-06-09 11:13 ` [PATCH V11 00/10] arm64/perf: Enable branch stack sampling Anshuman Khandual
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=ZH8NTSYMS4n2/edR@FVFF77S0Q05N.cambridge.arm.com \
--to=mark.rutland@arm.com \
--cc=acme@kernel.org \
--cc=anshuman.khandual@arm.com \
--cc=broonie@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=james.clark@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=maz@kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=robh@kernel.org \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).