Apparently there exist certain workloads which rely heavily on software
checksumming, for which the generic do_csum() implementation becomes a
significant bottleneck. Therefore let's give arm64 its own optimised
version - for ease of maintenance this foregoes assembly or intrisics,
and is thus not actually arm64-specific, but does rely heavily on C
idioms that translate well to the A64 ISA and the typical load/store
capabilities of most ARMv8 CPU cores.
The resulting increase in checksum throughput scales nicely with buffer
size, tending towards 4x for a small in-order core (Cortex-A53), and up
to 6x or more for an aggressive big core (Ampere eMAG).
Reported-by: Lingyan Huang <huanglingyan2@huawei.com>
Tested-by: Lingyan Huang <huanglingyan2@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ARM64 implementation of ip_fast_csum() do most of the work
in 128 or 64 bit and call csum_fold() to finalize. csum_fold()
itself take a __wsum argument, to insure that this value is
always a 32bit native-order value.
Fix this by adding the sadly needed '__force' to cast the native
'sum' to the type '__wsum'.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
AArch64 is capable of 128-bit memory accesses without alignment
restrictions, which makes it both possible and highly practical to slurp
up a typical 20-byte IP header in just 2 loads. Implement our own
version of ip_fast_checksum() to take advantage of that, resulting in
considerably fewer instructions and memory accesses than the generic
version. We can also get more optimal code generation for csum_fold() by
defining it a slightly different way round from the generic version, so
throw that into the mix too.
Suggested-by: Luke Starrett <luke.starrett@broadcom.com>
Acked-by: Luke Starrett <luke.starrett@broadcom.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
