Re: Degraded performance in cat + patch

[Pádraig Brady]

Jim Meyering wrote:
> 
>>From 6dd9c564a0cba6eec95102f091c6692a5ab48876 Mon Sep 17 00:00:00 2001
> From: Jim Meyering <address@hidden>
> Date: Fri, 6 Mar 2009 10:27:43 +0100
> Subject: [PATCH] cat: use larger buffer sizes to reduce read/write-syscall 
> overhead
> 
> * src/cat.c (max): Remove definition.  Use MAX from system.h instead.
> (compute_buffer_size): New function.
> (main): Use it, to compute larger input and output buffer sizes
> derived from st_blksize, now typically 32KiB rather than 4KiB.
> Suggestion from Tzvi Rotshtein.

That sounds like previously cat did not derive from st_blksize
and that st_blksize is typically 32KiB :) Suggested log message:

* src/cat.c (max): Remove definition.  Use MAX from system.h instead.
(compute_buffer_size): New function to compute the input and output
buffer sizes, which are now set at 8 times st_blksize with
a minimum of 32KiB. Previously the typical block sizes used were
1KiB for pipes and 4KiB for files.
(main): Use it.
This was seem to increase throughput by up to 50%.
Suggestion from Tzvi Rotshtein.

cheers,
Pádraig.