From: Charlie Jenkins <charlie@rivosinc.com>
To: Charlie Jenkins <charlie@rivosinc.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Conor Dooley <conor@kernel.org>,
Samuel Holland <samuel.holland@sifive.com>,
David Laight <David.Laight@aculab.com>,
Xiao Wang <xiao.w.wang@intel.com>,
Evan Green <evan@rivosinc.com>,
linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>, Arnd Bergmann <arnd@arndb.de>,
David Laight <david.laight@aculab.com>
Subject: [PATCH v8 1/5] asm-generic: Improve csum_fold
Date: Fri, 27 Oct 2023 15:43:51 -0700 [thread overview]
Message-ID: <20231027-optimize_checksum-v8-1-feb7101d128d@rivosinc.com> (raw)
In-Reply-To: <20231027-optimize_checksum-v8-0-feb7101d128d@rivosinc.com>
This csum_fold implementation introduced into arch/arc by Vineet Gupta
is better than the default implementation on at least arc, x86, and
riscv. Using GCC trunk and compiling non-inlined version, this
implementation has 41.6667%, 25% fewer instructions on riscv64, x86-64
respectively with -O3 optimization. Most implmentations override this
default in asm, but this should be more performant than all of those
other implementations except for arm which has barrel shifting and
sparc32 which has a carry flag.
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Reviewed-by: David Laight <david.laight@aculab.com>
---
include/asm-generic/checksum.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/checksum.h b/include/asm-generic/checksum.h
index 43e18db89c14..ad928cce268b 100644
--- a/include/asm-generic/checksum.h
+++ b/include/asm-generic/checksum.h
@@ -2,6 +2,8 @@
#ifndef __ASM_GENERIC_CHECKSUM_H
#define __ASM_GENERIC_CHECKSUM_H
+#include <linux/bitops.h>
+
/*
* computes the checksum of a memory block at buff, length len,
* and adds in "sum" (32-bit)
@@ -31,9 +33,7 @@ extern __sum16 ip_fast_csum(const void *iph, unsigned int ihl);
static inline __sum16 csum_fold(__wsum csum)
{
u32 sum = (__force u32)csum;
- sum = (sum & 0xffff) + (sum >> 16);
- sum = (sum & 0xffff) + (sum >> 16);
- return (__force __sum16)~sum;
+ return (__force __sum16)((~sum - ror32(sum, 16)) >> 16);
}
#endif
--
2.42.0
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2023-10-27 22:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-27 22:43 [PATCH v8 0/5] riscv: Add fine-tuned checksum functions Charlie Jenkins
2023-10-27 22:43 ` Charlie Jenkins [this message]
2023-10-27 23:10 ` [PATCH v8 1/5] asm-generic: Improve csum_fold Al Viro
2023-10-28 0:04 ` Charlie Jenkins
2023-10-27 22:43 ` [PATCH v8 2/5] riscv: Add static key for misaligned accesses Charlie Jenkins
2023-10-27 22:43 ` [PATCH v8 3/5] riscv: Checksum header Charlie Jenkins
2023-10-31 9:11 ` Wang, Xiao W
2023-10-31 22:53 ` Charlie Jenkins
2023-10-27 22:43 ` [PATCH v8 4/5] riscv: Add checksum library Charlie Jenkins
2023-10-31 9:51 ` Wang, Xiao W
2023-10-31 22:59 ` Charlie Jenkins
2023-10-27 22:43 ` [PATCH v8 5/5] riscv: Test checksum functions Charlie Jenkins
2023-10-31 7:57 ` [PATCH v8 0/5] riscv: Add fine-tuned " Conor Dooley
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20231027-optimize_checksum-v8-1-feb7101d128d@rivosinc.com \
--to=charlie@rivosinc.com \
--cc=David.Laight@aculab.com \
--cc=aou@eecs.berkeley.edu \
--cc=arnd@arndb.de \
--cc=conor@kernel.org \
--cc=evan@rivosinc.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=samuel.holland@sifive.com \
--cc=xiao.w.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).