maybe I should just disable the background writer and disable read
aheads.
since I am working on a database, its doing its own caching.
can it be done?
Regards,
tzahi.
> -----Original Message-----
> From: Muli Ben-Yehuda [mailto:[EMAIL PROTECTED]
> Sent: Thursday, January 13, 2005 12:18 AM
> To: guy keren
> Cc: Tzahi Fadida; linux-il@cs.huji.ac.il
> Subject: Re: Getting io statistics on processes.
>
>
> On Thu, Jan 13, 2005 at 12:29:01AM +0200, guy keren wrote:
>
> > in fact, it's very hard to achieve a proper "which process
> caused this
> > I/O" log. consider the case where two processes wrote to the same
> > position in a file - there's likely to be only one disk write
> > operation - which of the two processes will you account this I/O
> > against?
>
> Whichever caused this block to be read into the page cache.
>
> > also, what about read-ahead? when a process reads data from
> the disk,
> > the operating system typically performs a read-ahead. in fact,
> > sometimes the mere opening of a file will cause the VFS layer to
> > perform read-ahead of data for the file - even if your application
> > didn't read anything.
>
> That's IO caused on behalf of the process.
>
> > thus, you should try to _properly_ define what is it that you're
> > trying to account for, including those 'multiple updates -
> single disk
> > I/O' and 'read ahead' cases.
>
> I fully support this statement :-)
>
> Cheers,
> Muli
> --
> Muli Ben-Yehuda
> http://www.mulix.org | http://mulix.livejournal.com/
>
>
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