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Re: [PATCH] blk: improve order of bio handling in generic_make_request()

From NeilBrown <neilb@suse.com>
Newsgroups linux.kernel
Subject Re: [PATCH] blk: improve order of bio handling in generic_make_request()
Date 2017-03-06 05:50 +0100
Message-ID <thSKR-2BN-13@gated-at.bofh.it> (permalink)
References <tgNNg-4Jz-3@gated-at.bofh.it> <tgRQS-7Cb-7@gated-at.bofh.it>
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On Fri, Mar 03 2017, Jack Wang wrote:
>
> Thanks Neil for pushing the fix.
>
> We can optimize generic_make_request a little bit:
> - assign bio_list struct hold directly instead init and merge
> - remove duplicate code
>
> I think better to squash into your fix.

Hi Jack,
 I don't object to your changes, but I'd like to see a response from
 Jens first.
 My preference would be to get the original patch in, then other changes
 that build on it, such as this one, can be added.  Until the core
 changes lands, any other work is pointless.

 Of course if Jens wants a this merged before he'll apply it, I'll
 happily do that.

Thanks,
NeilBrown



> ---
>  block/blk-core.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 3bc7202..b29b7e5 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -2147,8 +2147,7 @@ blk_qc_t generic_make_request(struct bio *bio)
>  			struct bio_list lower, same, hold;
>  
>  			/* Create a fresh bio_list for all subordinate requests */
> -			bio_list_init(&hold);
> -			bio_list_merge(&hold, &bio_list_on_stack);
> +			hold = bio_list_on_stack;
>  			bio_list_init(&bio_list_on_stack);
>  
>  			ret = q->make_request_fn(q, bio);
> @@ -2168,14 +2167,10 @@ blk_qc_t generic_make_request(struct bio *bio)
>  			bio_list_merge(&bio_list_on_stack, &lower);
>  			bio_list_merge(&bio_list_on_stack, &same);
>  			bio_list_merge(&bio_list_on_stack, &hold);
> -
> -			bio = bio_list_pop(current->bio_list);
>  		} else {
> -			struct bio *bio_next = bio_list_pop(current->bio_list);
> -
>  			bio_io_error(bio);
> -			bio = bio_next;
>  		}
> +		bio = bio_list_pop(current->bio_list);
>  	} while (bio);
>  	current->bio_list = NULL; /* deactivate */
>  
> -- 
>
> Regards,
> Jack 

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Thread

[PATCH] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-03 06:20 +0100
  Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Jack Wang <jinpu.wang@profitbricks.com> - 2017-03-03 10:40 +0100
    Re: [PATCH] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-06 05:50 +0100
      Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Jack Wang <jinpu.wang@profitbricks.com> - 2017-03-06 10:50 +0100
        Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Pavel Machek <pavel@ucw.cz> - 2017-03-07 16:50 +0100
          Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Jens Axboe <axboe@kernel.dk> - 2017-03-07 17:30 +0100
          Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Jack Wang <jinpu.wang@profitbricks.com> - 2017-03-07 20:00 +0100
      Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Jens Axboe <axboe@kernel.dk> - 2017-03-07 03:10 +0100
        Re: [PATCH] blk: improve order of bio handling in  generic_make_request() Jack Wang <jinpu.wang@profitbricks.com> - 2017-03-07 10:00 +0100
          Re: blk: improve order of bio handling in generic_make_request() Jens Axboe <axboe@kernel.dk> - 2017-03-07 18:20 +0100
            Re: blk: improve order of bio handling in generic_make_request() Mike Snitzer <snitzer@redhat.com> - 2017-03-07 18:40 +0100
              Re: blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-07 22:20 +0100
                Re: blk: improve order of bio handling in generic_make_request() Mike Snitzer <snitzer@redhat.com> - 2017-03-08 02:00 +0100
                Re: blk: improve order of bio handling in generic_make_request() Mikulas Patocka <mpatocka@redhat.com> - 2017-03-08 18:00 +0100
                Re: blk: improve order of bio handling in generic_make_request() Lars Ellenberg <lars.ellenberg@linbit.com> - 2017-03-08 18:40 +0100
                Re: blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-09 07:10 +0100
          Re: blk: improve order of bio handling in generic_make_request() Mike Snitzer <snitzer@redhat.com> - 2017-03-07 18:50 +0100
            Re: blk: improve order of bio handling in generic_make_request() Lars Ellenberg <lars.ellenberg@linbit.com> - 2017-03-08 14:00 +0100
        [PATCH v2] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-07 21:50 +0100
          Re: [PATCH v2] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-10 05:40 +0100
            [PATCH 5/5] block_dev: make blkdev_dio_pool a non-rescuing bioset NeilBrown <neilb@suse.com> - 2017-03-10 05:40 +0100
            Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Jens Axboe <axboe@kernel.dk> - 2017-03-10 05:40 +0100
              Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Jens Axboe <axboe@kernel.dk> - 2017-03-10 05:50 +0100
              Re: [PATCH v2] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-10 06:20 +0100
                Re: [PATCH v2] blk: improve order of bio handling in generic_make_request() Lars Ellenberg <lars.ellenberg@linbit.com> - 2017-03-10 13:40 +0100
                Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Mike Snitzer <snitzer@redhat.com> - 2017-03-10 15:40 +0100
                Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Mikulas Patocka <mpatocka@redhat.com> - 2017-03-10 16:00 +0100
                Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Jack Wang <jinpu.wang@profitbricks.com> - 2017-03-10 16:20 +0100
                Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Mike Snitzer <snitzer@redhat.com> - 2017-03-10 16:40 +0100
                Re: [PATCH v2] blk: improve order of bio handling in  generic_make_request() Lars Ellenberg <lars.ellenberg@linbit.com> - 2017-03-10 20:00 +0100
                Re: [PATCH v2] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-11 01:50 +0100
            [PATCH 1/5 v3] blk: improve order of bio handling in generic_make_request() NeilBrown <neilb@suse.com> - 2017-03-10 05:40 +0100
            [PATCH 3/5] blk: make the bioset rescue_workqueue optional. NeilBrown <neilb@suse.com> - 2017-03-10 05:40 +0100
            [PATCH 4/5] blk: use non-rescuing bioset for q->bio_split. NeilBrown <neilb@suse.com> - 2017-03-10 05:40 +0100
            [PATCH 2/5] blk: remove bio_set arg from blk_queue_split() NeilBrown <neilb@suse.com> - 2017-03-10 05:40 +0100

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