From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Raphael M Zinsly <rzinsly@linux.ibm.com>
Subject: Re: [PATCH v3 2/2] powerpc: Add optimized stpncpy for POWER9
Date: Wed, 30 Sep 2020 10:42:31 -0300 [thread overview]
Message-ID: <37dd785c-60ec-f064-bfeb-7c5ec5483936@linaro.org> (raw)
In-Reply-To: <20200929152103.18564-2-rzinsly@linux.ibm.com>
On 29/09/2020 12:21, Raphael Moreira Zinsly via Libc-alpha wrote:
> Add stpncpy support into the POWER9 strncpy.
The benchmark numbers you provided [1] seems to show it is slight worse than
the generic_strncpy which uses the same strategy as string/strncpy.c
(which would use VSX instruction through memset/memcpy). Did you compare this
optimization against an implementation that just call power8/9 memset/memcpy
instead?
It should resulting a smaller implementation which reduces i-cache size and
the code is much more simpler and maintainable. The same applies for stpncpy.
I tried to dissuade Intel developers that such micro-optimization are not
really a real gain and instead we should optimize only a handful of string
operations (memcpy/memset/etc.) and use composable implementation instead
(as generic strncpy). It still resulted on 1a153e47fcc, but I think we
might do better for powerpc.
[1] https://sourceware.org/pipermail/libc-alpha/2020-September/118049.html
next prev parent reply other threads:[~2020-09-30 13:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 15:21 [PATCH v3 1/2] powerpc: Add optimized strncpy " Raphael Moreira Zinsly
2020-09-29 15:21 ` [PATCH v3 2/2] powerpc: Add optimized stpncpy " Raphael Moreira Zinsly
2020-09-29 15:23 ` Raphael M Zinsly
2020-09-30 13:42 ` Adhemerval Zanella [this message]
2020-09-30 14:21 ` Raphael M Zinsly
2020-09-30 14:46 ` Adhemerval Zanella
2020-11-12 17:12 ` Tulio Magno Quites Machado Filho
2020-09-29 15:22 ` [PATCH v3 1/2] powerpc: Add optimized strncpy " Raphael M Zinsly
2020-10-15 15:20 ` Lucas A. M. Magalhaes
2020-11-12 17:09 ` Tulio Magno Quites Machado Filho
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