Messages in this thread | | | Date | Tue, 7 Sep 2004 11:35:59 +0200 | From | Jens Axboe <> | Subject | Re: [patch 1/3] uml-ubd-no-empty-queue |
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On Mon, Sep 06 2004, blaisorblade_spam@yahoo.it wrote: > > Avoid using, in the UBD driver, the elv_queue_empty function. It's for > the block layer only; in fact, the Anticipatory Scheduler can return NULL > with elv_next_request() even if the queue is not empty, because it waits > for the process to send another request before seeking on the disk. > > In fact, if (with uml-ubd-any-elevator) we let UBD use any scheduler, > elevator=as will make the UBD driver Oops, if we don't have this patch. > > Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it> > --- > > uml-linux-2.6.8.1-paolo/arch/um/drivers/ubd_kern.c | 6 ++---- > 1 files changed, 2 insertions(+), 4 deletions(-) > > diff -puN arch/um/drivers/ubd_kern.c~uml-ubd-no-empty-queue arch/um/drivers/ubd_kern.c > --- uml-linux-2.6.8.1/arch/um/drivers/ubd_kern.c~uml-ubd-no-empty-queue 2004-08-29 14:40:51.313410952 +0200 > +++ uml-linux-2.6.8.1-paolo/arch/um/drivers/ubd_kern.c 2004-08-29 14:40:51.315410648 +0200 > @@ -1038,8 +1038,7 @@ static void do_ubd_request(request_queue > int err, n; > > if(thread_fd == -1){ > - while(!elv_queue_empty(q)){ > - req = elv_next_request(q); > + while((req = elv_next_request(q)) != NULL){ > err = prepare_request(req, &io_req); > if(!err){ > do_io(&io_req); > @@ -1048,9 +1047,8 @@ static void do_ubd_request(request_queue > } > } > else { > - if(do_ubd || elv_queue_empty(q)) > + if(do_ubd || (req = elv_next_request(q)) == NULL) > return; > - req = elv_next_request(q); > err = prepare_request(req, &io_req); > if(!err){ > do_ubd = ubd_handler;
Patch is correct.
-- Jens Axboe
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