GNU bug report logs - #32073
Improvements in Grep

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Sergiu Hlihor <sh <at> discovergy.com>
To: bug-grep <at> gnu.org
Subject: Improvements in Grep
Date: Fri, 6 Jul 2018 18:26:17 +0200

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Hello,
     I'm using grep over Ubuntu Server 14.04 (Grep version 2.16). While
grepping over large files I've noticed Grep is painfully slow. The
bottleneck seems to be the read block which is extremely low (looks like
64KB). For large files residing over big HDD RAID arrays, this request
barely reaches one drive and based on CPU usage, grep is idling more or
less. Given my tests for such scenarios, a read block size of at least
512KB would be way more efficient. It's very likely that optimum would be
1MB+. Also, such increase in buffer size would also benefit slightly SSDs
where maximum sequential throughput is usually achieved when reading at
256KB+ block size.
     If this is already possible in newer versions or configurable, I'd
appreciate some hints about the new version which contains or about the way
I can configure it to increase the read block size.

Thanks and best regards,
Sergiu

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