Andre Hedrick <andre@linux-ide.org> writes:
> On Thu, 18 May 2000, Alan Cox wrote:
>
> > Find out what has ruined disk I/O throughput.
>
> Possible combination elevator conflict with disk hardware.
> If internal device write buffer cache sorting is enabled, you have double
> labor for a single task. The rules for the elevator may conflict with the
> drives look-ahead/read-ahead tables on the drive (OEM rules apply).
One of the sources of poor performance under moderate/heavy disk I/O is the
current management of the request pool. It is exhausted quite easily and it
causes an insane number of sleeps/wake-ups. I have seen situations where
each attempt to acquire a request structure loops through sleep/wake-up an
average of 10 times. Each time we wake up we have to scan the whole pool
linearly, destroying the data cache in the process, and chances are we will
fail and will need to do it all over. The elevator has only exacerbated the
situation, with default settings at least.
-- Dimitris Michailidis dimitris@engr.sgi.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
This archive was generated by hypermail 2b29 : Tue May 23 2000 - 21:00:16 EST