Re: The cause of the "VM" performance problem with 2.4.X

From: Jens Axboe (axboe@suse.de)
Date: Wed Aug 29 2001 - 03:25:10 EST


On Wed, Aug 29 2001, Jens Axboe wrote:
> > > 4.51 432.97 25.70 13445261 0.00 0.00 blk_get_queue
> >
> > Now, while I don't worry about "getblk()" itself, the request stuff and
> > blk_get_queue() _can_ be quite an issue even under non-mkfs load, so
>
> blk_get_queue() is easy to 'fix', it grabs io_request_lock for no good
> reason at all. I think this must have been a failed attempt to protect
> switching of queues, however it's obviously very broken in this regard.
> So in fact no skin is off our nose for just removing the io_request_lock
> in that path. 2.5 will have it properly reference counted...

Linus, will you take this patch to remove io_request_lock in this path?

-- 
Jens Axboe


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