From: Will Deacon <will@kernel.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>,
kan.liang@linux.intel.com, mingo@redhat.com, acme@kernel.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@redhat.com,
eranian@google.com, ak@linux.intel.com, dave.hansen@intel.com,
kirill.shutemov@linux.intel.com, benh@kernel.crashing.org,
paulus@samba.org, David Miller <davem@davemloft.net>
Subject: Re: [PATCH V9 1/4] perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE
Date: Mon, 12 Oct 2020 09:48:29 +0100 [thread overview]
Message-ID: <20201012084829.GA1151@willie-the-truck> (raw)
In-Reply-To: <877drz1qbc.fsf@mpe.ellerman.id.au>
On Sat, Oct 10, 2020 at 12:28:39AM +1100, Michael Ellerman wrote:
> Peter Zijlstra <peterz@infradead.org> writes:
> > Patch 4 makes it all far worse by exposing it to pretty much everybody.
> >
> > Now, I think we can fix at least the user mappings with the below delta,
> > but if archs are using non-page-table MMU sizes we'll need arch helpers.
> >
> > ARM64 is in that last boat.
>
> I think we probably need it to be weak so we can provide our own
> version.
I guess the same thing applies to us, but I can't really tell how accurate
this stuff needs to be for userspace. If it's trying to use the page-table
configuration to infer properties of the TLB, that's never going to be
reliable because the TLB can choose both to split and coalesce entries
as long as software can't tell.
Will
next prev parent reply other threads:[~2020-10-12 8:48 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 13:57 [PATCH V9 0/4] Add the page size in the perf record (kernel) kan.liang
2020-10-01 13:57 ` [PATCH V9 1/4] perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE kan.liang
2020-10-09 9:09 ` Peter Zijlstra
2020-10-09 9:16 ` Peter Zijlstra
2020-10-09 9:37 ` Will Deacon
2020-10-09 9:53 ` Peter Zijlstra
2020-10-20 2:49 ` Leo Yan
2020-10-20 7:19 ` Peter Zijlstra
2020-10-20 8:16 ` Leo Yan
2020-10-09 12:29 ` Liang, Kan
2020-10-09 12:57 ` Peter Zijlstra
2020-10-09 13:28 ` Michael Ellerman
2020-10-12 8:48 ` Will Deacon [this message]
2020-10-13 14:57 ` Liang, Kan
2020-10-13 15:46 ` Peter Zijlstra
2020-10-13 16:34 ` Peter Zijlstra
2020-11-04 17:11 ` Liang, Kan
2020-11-10 15:20 ` Liang, Kan
2020-11-11 9:57 ` Peter Zijlstra
2020-11-11 11:22 ` Peter Zijlstra
2020-11-11 12:43 ` Peter Zijlstra
2020-11-11 15:30 ` Matthew Wilcox
2020-11-11 15:52 ` Peter Zijlstra
2020-11-11 15:57 ` Peter Zijlstra
2020-11-11 16:38 ` Matthew Wilcox
2020-11-11 17:22 ` Peter Zijlstra
2020-11-11 18:26 ` Matthew Wilcox
2020-11-11 20:00 ` Peter Zijlstra
2020-11-11 22:33 ` Matthew Wilcox
2020-11-12 9:53 ` Peter Zijlstra
2020-11-12 11:36 ` Peter Zijlstra
2020-11-12 14:01 ` Matthew Wilcox
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Kan Liang
2020-10-01 13:57 ` [PATCH V9 2/4] perf/x86/intel: Support PERF_SAMPLE_DATA_PAGE_SIZE kan.liang
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Kan Liang
2020-10-01 13:57 ` [PATCH V9 3/4] powerpc/perf: " kan.liang
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Kan Liang
2020-10-01 13:57 ` [PATCH V9 4/4] perf/core: Add support for PERF_SAMPLE_CODE_PAGE_SIZE kan.liang
2020-10-29 10:51 ` [tip: perf/core] " tip-bot2 for Stephane Eranian
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