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Re: [PATCH v2] Improve performance of strstr
- From: Wilco Dijkstra <Wilco dot Dijkstra at arm dot com>
- To: Rich Felker <dalias at libc dot org>
- Cc: 'GNU C Library' <libc-alpha at sourceware dot org>, nd <nd at arm dot com>
- Date: Wed, 2 Jan 2019 13:40:54 +0000
- Subject: Re: [PATCH v2] Improve performance of strstr
- References: <DB5PR08MB1030CDDFA10DCA6E414A844683B20@DB5PR08MB1030.eurprd08.prod.outlook.com>,<20181231212423.GR23599@brightrain.aerifal.cx>
Hi Rich,
> This is a major performance regression and should not be committed.
Exactly which case regresses? I'd love to hear about it since I can't find
any.
> The test case does not cover anything near the worst cases. With a
> limit more like 16 bytes it might be reasonable but 256 is plenty
> large to see the quadratic effects (64k is a big number).
We currently don't have a good strstr benchmark in GLIBC, which is why
I posted a patch to improve this. If you have further suggestions how to
improve it just let me know.
Cheers,
Wilco