question about access_log buffer size

[yong xue]

2010/2/25 Igor Sysoev <igor at sysoev.ru>

> On Thu, Feb 25, 2010 at 01:16:04PM +0800, yong xue wrote:
>
> > The *access_log* directive sets the path, format and buffer size for the
> > access log file. Using "off" as the only parameter clears all
> > *access_log* directives
> > for the current level. If the format is not indicated, it defaults to
> > "combined" <http://wiki.nginx.org/NginxHttpLogModule#log_format_combined
> >.
> > The size of buffer must not exceed the size of the atomic record for
> writing
> > into the disk file. This size is not limited for FreeBSD 3.0-6.0.
> >
> > this is quoted from wiki.nginx.org.
> > My server is running linux 2.6.16.
> > I dont know the size of the atomic record for writing into the disk file.
> > Can somebody help me?
> >
> > I googled, but cannot make sure that  the linux write system call is
> atomic.
>
> Linux shell ensure atomic write for PIP_BUF, i.e. 4K. However, I believe
> this value is much more for regular files, so you may try to set 32k.
>
>
> thanks.

so the size depends on the implementation. And the access log is not much
serious.
I will do some reading on the kernel later if i have time.


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