From: Siddhesh Poyarekar <siddhesh@gotplt.org>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH 1/3] Guess L1 cache linesize for aarch64
Date: Tue, 10 Oct 2017 10:37:00 -0000 [thread overview]
Message-ID: <24591e6b-7da9-bd03-626c-6d4618e84da0@gotplt.org> (raw)
In-Reply-To: <59DC9EC6.5080606@arm.com>
On Tuesday 10 October 2017 03:49 PM, Szabolcs Nagy wrote:
> On 08/06/17 23:57, Richard Henderson wrote:
>> + /* Unfortunately, the registers that contain the actual cache info
>> + (CCSIDR_EL1, CLIDR_EL1, and CSSELR_EL1) are protected by the Linux
>> + kernel (though they need not have been). However, CTR_EL0 contains
>> + the *minimum* linesize in the entire cache hierarchy, and is
>> + accessible to userland, for use in __aarch64_sync_cache_range,
>> + and it is a reasonable assumption that the L1 cache will have that
>> + minimum line size. */
>
> maybe
Right, but that's an architectural detail that may not be relevant for
sysconf. That is, the assumption may be suitable for the way the
sysconf is typically used.
>> + case _SC_LEVEL1_ICACHE_LINESIZE:
>> + case _SC_LEVEL1_DCACHE_LINESIZE:
>
> i can't find documentation for these, what meaning do users expect?
Applications may use these hints to try and align their code/data
suitably or read/write data in an optimal manner. It needs to be
documented and I hope to have a patch ready for it soon, but I wanted to
be sure that this patch was in place since otherwise the documentation
does not make sense.
Siddhesh
next prev parent reply other threads:[~2017-10-10 10:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-08 22:57 [PATCH 0/3] Add some missing cache infomation Richard Henderson
2017-06-08 22:57 ` [PATCH 3/3] Add cache info for powerpc64 Richard Henderson
2017-06-09 6:59 ` Florian Weimer
2017-06-09 13:12 ` Tulio Magno Quites Machado Filho
2017-06-09 20:07 ` Richard Henderson
2017-06-08 22:57 ` [PATCH 1/3] Guess L1 cache linesize for aarch64 Richard Henderson
2017-06-09 5:51 ` Siddhesh Poyarekar
2017-06-09 5:52 ` Andrew Pinski
2017-10-10 7:24 ` Siddhesh Poyarekar
2017-10-10 10:20 ` Szabolcs Nagy
2017-10-10 10:37 ` Siddhesh Poyarekar [this message]
2017-10-10 11:01 ` Szabolcs Nagy
2017-10-10 11:56 ` Siddhesh Poyarekar
2017-10-10 14:20 ` Richard Henderson
2017-10-11 5:28 ` Siddhesh Poyarekar
2017-10-10 17:19 ` Szabolcs Nagy
2017-06-08 22:57 ` [PATCH 2/3] Add hidden_proto for getauxval Richard Henderson
2017-06-09 5:55 ` Siddhesh Poyarekar
2017-06-09 6:58 ` Florian Weimer
2017-06-09 17:45 ` Richard Henderson
2017-06-09 17:49 ` Florian Weimer
2017-06-09 22:11 ` Richard Henderson
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