Re: [PATCH 0/4] linux-2.6-block: deactivating pagecache for benchmarks

[Jens Axboe <axboe@suse.de>]

On Thu, Dec 01 2005, Dirk Henning Gerdes wrote:
> Hi Jens!
> 
> For doing benchmarks on the I/O-Schedulers, I thought it would be very
> useful to disable the pagecache.
> 
> I didn't want to make it so complicated so I just mark pages as
> not-uptodate, so they have to be read again. Another reason was, that I
> wanted to keep the conditions as near to reality as possible.
> 
> Further I thought it would be useful, if you could turn the pagecache on
> and off without rebooting the system.
> 
> I implemented a proc-fs entry "/proc/benchmark/pagecache" for this.
> 
> Probably this patch can be useful for anyone else, who wants to do  some
> benchmarks on block-layer stuff.
> And if not, I would appreciate if you could have a look on it.

This is rather odd, if you ask me, I don't like it. If you are doing
serious benchmarking, you do it on a seperate disk / file system which
you can just umount/mount before starting over. Or you reboot the
machine in between.

-- 
Jens Axboe