linux-kernel - Re: [PATCH V3 01/13] perf/core, x86: Add PERF_SAMPLE_DATA_PAGE

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Date:   Fri, 1 Feb 2019 05:02:21 +0000
From:   Will Deacon <will.deacon@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     kan.liang@...ux.intel.com, acme@...nel.org, tglx@...utronix.de,
        mingo@...hat.com, linux-kernel@...r.kernel.org, eranian@...gle.com,
        jolsa@...hat.com, namhyung@...nel.org, ak@...ux.intel.com,
        Andy Lutomirski <luto@...capital.net>
Subject: Re: [PATCH V3 01/13] perf/core, x86: Add PERF_SAMPLE_DATA_PAGE_SIZE

On Thu, Jan 31, 2019 at 01:37:25PM +0100, Peter Zijlstra wrote:
> On Wed, Jan 30, 2019 at 06:23:42AM -0800, kan.liang@...ux.intel.com wrote:
> > +enum perf_page_size {
> > +	PERF_PAGE_SIZE_NONE,
> > +	PERF_PAGE_SIZE_4K,
> > +	PERF_PAGE_SIZE_8K,
> > +	PERF_PAGE_SIZE_16K,
> > +	PERF_PAGE_SIZE_64K,
> > +	PERF_PAGE_SIZE_2M,
> > +	PERF_PAGE_SIZE_1G,
> > +	PERF_PAGE_SIZE_512G,
> > +};
> 
> Since you have a u64 to store this in, WTH do you use this limited enum?
> Are you very sure this covers all the possible page sizes for all
> architectures?

FWIW, this covers the basic page sizes on arm64, but it doesn't cover all of
the hugepage sizes.

Will