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Re: [Patch] aarch64: ThunderX2 specific memcpy and memmove
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: "Saikat dot Saharoy at cavium dot com" <Saikat dot Saharoy at cavium dot com>, "libc-alpha at sourceware dot org" <libc-alpha at sourceware dot org>
- Cc: nd <nd at arm dot com>
- Date: Tue, 30 May 2017 12:23:24 +0000
- Subject: Re: [Patch] aarch64: ThunderX2 specific memcpy and memmove
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Hi Saikat,
Is this the correct patch you intended to post? I'm asking because
neither memcpy nor memmove pass any tests (it's obvious from the
patch that the overlap case is completely missing from memmove),
the code is absolutely humongous (17KB!!!) and very inefficient due to
using inline assembler.
For any resubmission I'd recommend you first run all GLIBC tests and
benchmarks plus do a SPEC comparison run against the generic memcpy.
Due to the huge size and large number of branches I would expect it
to be significantly slower in the real world, even if it seems faster in
some microbenchmarks. glibc/benchtests/bench-memcpy-random is a
quick way to verify this as it is based on the memcpy size distribution
in SPEC.
Cheers,
Wilco