From: "Todd C. Miller" <millert@openbsd.org>
Subject: Re: optimise reading the file index
To: Christian Weisgerber <naddy@mips.inka.de>
Cc: gameoftrees@openbsd.org
Date: Thu, 27 Jul 2023 09:07:13 -0600

On Thu, 27 Jul 2023 15:19:47 +0200, Christian Weisgerber wrote:

> The current code uses fread(3), i.e., buffered stdio, which translates
> to a long series of 16 kB read(2) system calls.

stdio uses the "optimal" buffer size reported for the device,
st_blksize from struct stat.  The buffer size can be modified via
a call to setvbuf().  The defaults were created when memory was
more dear so you may be able to improve things by just bumping the
buffer size.

> For a got status of /usr/src, 786 read(2) calls look rather negligible
> compared to 92,300+ stat(2) calls.

Yikes, that is a lot.

 - todd