Re: Big git diff speedup by avoiding x86 "fast string" memcmp

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Boaz Harrosh <bharrosh@xxxxxxxxxxx>
Date: Wed, 15 Dec 2010 15:15:09 +0200

> I agree that the byte-compare or long-compare should give you very close
> results in modern pipeline CPUs. But surly 12 increments-and-test should
> show up against 3 (or even 2). I would say it must be a better plan.

For strings of these lengths the setup code necessary to initialize
the inner loop and the tail code to handle the sub-word ending cases
eliminate whatever gains there are.

I know this as I've been hacking on assembler optimized strcmp() and
memcmp() in my spare time over the past year or so.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux