Messages in this thread | | | Date | Wed, 1 Jul 2009 11:32:35 +0200 | From | Jens Axboe <> | Subject | Re: [PATCH 2/2] cfq-iosched: get rid of the need for __GFP_FAIL in cfq_find_alloc_queue() |
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On Wed, Jul 01 2009, Shan Wei wrote: > Jens Axboe said: > > Setup an emergency fallback cfqq that we allocate at IO scheduler init > > time. If the slab allocation fails in cfq_find_alloc_queue(), we'll just > > punt IO to that cfqq instead. This ensures that cfq_find_alloc_queue() > > never fails without having to ensure free memory. > > > > Signed-off-by: Jens Axboe <jens.axboe@oracle.com> > > --- > > > > @@ -1740,11 +1745,8 @@ cfq_get_queue(struct cfq_data *cfqd, int is_sync, struct io_context *ioc, > > cfqq = *async_cfqq; > > } > > > > - if (!cfqq) { > > + if (!cfqq) > > cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); > > - if (!cfqq) > > - return NULL; > > - } > > I jsut reviewed the code and found that the check of cfqq is also redundant > after doing cfq_get_queue() in cfq_set_request. > > The patch is based on Linus's main tree.
It's not redundant in Linus' tree, cfq_get_queue() can return NULL for != __GFP_WAIT.
> > Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com> > --- > block/cfq-iosched.c | 4 ---- > 1 files changed, 0 insertions(+), 4 deletions(-) > > diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c > index 833ec18..c373237 100644 > --- a/block/cfq-iosched.c > +++ b/block/cfq-iosched.c > @@ -2307,10 +2307,6 @@ cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask) > cfqq = cic_to_cfqq(cic, is_sync); > if (!cfqq) { > cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask); > - > - if (!cfqq) > - goto queue_fail; > - > cic_set_cfqq(cic, cfqq, is_sync); > } >
-- Jens Axboe
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