From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 9 Jan 2018 22:33:41 +0800 From: Ming Lei To: Dmitry Osipenko Cc: Jens Axboe , Christoph Hellwig , Alexander Viro , Kent Overstreet , Huang Ying , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Theodore Ts'o , "Darrick J . Wong" , Coly Li , Filipe Manana , Ulf Hansson , linux-mmc@vger.kernel.org Subject: Re: [PATCH V4 13/45] block: blk-merge: try to make front segments in full size Message-ID: <20180109143339.GC4356@ming.t460p> References: <20171218122247.3488-1-ming.lei@redhat.com> <20171218122247.3488-14-ming.lei@redhat.com> <20180109023432.GB31067@ming.t460p> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Jan 09, 2018 at 04:18:39PM +0300, Dmitry Osipenko wrote: > On 09.01.2018 05:34, Ming Lei wrote: > > On Tue, Jan 09, 2018 at 12:09:27AM +0300, Dmitry Osipenko wrote: > >> On 18.12.2017 15:22, Ming Lei wrote: > >>> When merging one bvec into segment, if the bvec is too big > >>> to merge, current policy is to move the whole bvec into another > >>> new segment. > >>> > >>> This patchset changes the policy into trying to maximize size of > >>> front segments, that means in above situation, part of bvec > >>> is merged into current segment, and the remainder is put > >>> into next segment. > >>> > >>> This patch prepares for support multipage bvec because > >>> it can be quite common to see this case and we should try > >>> to make front segments in full size. > >>> > >>> Signed-off-by: Ming Lei > >>> --- > >>> block/blk-merge.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- > >>> 1 file changed, 49 insertions(+), 5 deletions(-) > >>> > >>> diff --git a/block/blk-merge.c b/block/blk-merge.c > >>> index a476337a8ff4..42ceb89bc566 100644 > >>> --- a/block/blk-merge.c > >>> +++ b/block/blk-merge.c > >>> @@ -109,6 +109,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>> bool do_split = true; > >>> struct bio *new = NULL; > >>> const unsigned max_sectors = get_max_io_size(q, bio); > >>> + unsigned advance = 0; > >>> > >>> bio_for_each_segment(bv, bio, iter) { > >>> /* > >>> @@ -134,12 +135,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>> } > >>> > >>> if (bvprvp && blk_queue_cluster(q)) { > >>> - if (seg_size + bv.bv_len > queue_max_segment_size(q)) > >>> - goto new_segment; > >>> if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) > >>> goto new_segment; > >>> if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) > >>> goto new_segment; > >>> + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { > >>> + /* > >>> + * On assumption is that initial value of > >>> + * @seg_size(equals to bv.bv_len) won't be > >>> + * bigger than max segment size, but will > >>> + * becomes false after multipage bvec comes. > >>> + */ > >>> + advance = queue_max_segment_size(q) - seg_size; > >>> + > >>> + if (advance > 0) { > >>> + seg_size += advance; > >>> + sectors += advance >> 9; > >>> + bv.bv_len -= advance; > >>> + bv.bv_offset += advance; > >>> + } > >>> + > >>> + /* > >>> + * Still need to put remainder of current > >>> + * bvec into a new segment. > >>> + */ > >>> + goto new_segment; > >>> + } > >>> > >>> seg_size += bv.bv_len; > >>> bvprv = bv; > >>> @@ -161,6 +182,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>> seg_size = bv.bv_len; > >>> sectors += bv.bv_len >> 9; > >>> > >>> + /* restore the bvec for iterator */ > >>> + if (advance) { > >>> + bv.bv_len += advance; > >>> + bv.bv_offset -= advance; > >>> + advance = 0; > >>> + } > >>> } > >>> > >>> do_split = false; > >>> @@ -361,16 +388,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>> { > >>> > >>> int nbytes = bvec->bv_len; > >>> + unsigned advance = 0; > >>> > >>> if (*sg && *cluster) { > >>> - if ((*sg)->length + nbytes > queue_max_segment_size(q)) > >>> - goto new_segment; > >>> - > >>> if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) > >>> goto new_segment; > >>> if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) > >>> goto new_segment; > >>> > >>> + /* > >>> + * try best to merge part of the bvec into previous > >>> + * segment and follow same policy with > >>> + * blk_bio_segment_split() > >>> + */ > >>> + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { > >>> + advance = queue_max_segment_size(q) - (*sg)->length; > >>> + if (advance) { > >>> + (*sg)->length += advance; > >>> + bvec->bv_offset += advance; > >>> + bvec->bv_len -= advance; > >>> + } > >>> + goto new_segment; > >>> + } > >>> + > >>> (*sg)->length += nbytes; > >>> } else { > >>> new_segment: > >>> @@ -393,6 +433,10 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>> > >>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > >>> (*nsegs)++; > >>> + > >>> + /* for making iterator happy */ > >>> + bvec->bv_offset -= advance; > >>> + bvec->bv_len += advance; > >>> } > >>> *bvprv = *bvec; > >>> } > >>> > >> > >> Hello, > >> > >> This patch breaks MMC on next-20180108, in particular MMC doesn't work anymore > >> with this patch on NVIDIA Tegra20: > >> > >> <3>[ 36.622253] print_req_error: I/O error, dev mmcblk1, sector 512 > >> <3>[ 36.671233] print_req_error: I/O error, dev mmcblk2, sector 128 > >> <3>[ 36.711308] print_req_error: I/O error, dev mmcblk1, sector 31325304 > >> <3>[ 36.749232] print_req_error: I/O error, dev mmcblk2, sector 512 > >> <3>[ 36.761235] print_req_error: I/O error, dev mmcblk1, sector 31325816 > >> <3>[ 36.832039] print_req_error: I/O error, dev mmcblk2, sector 31259768 > >> <3>[ 99.793248] print_req_error: I/O error, dev mmcblk1, sector 31323136 > >> <3>[ 99.982043] print_req_error: I/O error, dev mmcblk1, sector 929792 > >> <3>[ 99.986301] print_req_error: I/O error, dev mmcblk1, sector 930816 > >> <3>[ 100.293624] print_req_error: I/O error, dev mmcblk1, sector 932864 > >> <3>[ 100.466839] print_req_error: I/O error, dev mmcblk1, sector 947200 > >> <3>[ 100.642955] print_req_error: I/O error, dev mmcblk1, sector 949248 > >> <3>[ 100.818838] print_req_error: I/O error, dev mmcblk1, sector 230400 > >> > >> Any attempt of mounting MMC block dev ends with a kernel crash. Reverting this > >> patch fixes the issue. > > > > Hi Dmitry, > > > > Thanks for your report! > > > > Could you share us what the segment limits are on your MMC? > > > > cat /sys/block/mmcN/queue/max_segment_size > > cat /sys/block/mmcN/queue/max_segments > > > > Please test the following patch to see if your issue can be fixed? > > > > --- > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index 446f63e076aa..cfab36c26608 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -431,12 +431,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > > > > sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > > (*nsegs)++; > > + } > > > > + *bvprv = *bvec; > > + if (advance) { > > /* for making iterator happy */ > > bvec->bv_offset -= advance; > > bvec->bv_len += advance; > > } > > - *bvprv = *bvec; > > } > > > > static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, > > Hi Ming, > > I've tried your patch and unfortunately it doesn't help with the issue. > > Here are the segment limits: > > # cat /sys/block/mmc*/queue/max_segment_size > 65535 Hi Dmitry, The 'max_segment_size' of 65535 should be the reason, could you test the following patch? --- diff --git a/block/blk-merge.c b/block/blk-merge.c index 446f63e076aa..38a66e3e678e 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -12,6 +12,8 @@ #include "blk.h" +#define sector_align(x) ALIGN_DOWN(x, 512) + static struct bio *blk_bio_discard_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -109,7 +111,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - unsigned advance = 0; + int advance = 0; bio_for_each_segment(bv, bio, iter) { /* @@ -144,8 +146,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, * bigger than max segment size, but this * becomes false after multipage bvecs. */ - advance = queue_max_segment_size(q) - seg_size; - + advance = sector_align( + queue_max_segment_size(q) - + seg_size); if (advance > 0) { seg_size += advance; sectors += advance >> 9; @@ -386,7 +389,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, { int nbytes = bvec->bv_len; - unsigned advance = 0; + int advance = 0; if (*sg && *cluster) { if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) @@ -400,8 +403,9 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, * blk_bio_segment_split() */ if ((*sg)->length + nbytes > queue_max_segment_size(q)) { - advance = queue_max_segment_size(q) - (*sg)->length; - if (advance) { + advance = sector_align(queue_max_segment_size(q) - + (*sg)->length); + if (advance > 0) { (*sg)->length += advance; bvec->bv_offset += advance; bvec->bv_len -= advance; @@ -431,12 +435,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); (*nsegs)++; + } + *bvprv = *bvec; + if (advance > 0) { /* for making iterator happy */ bvec->bv_offset -= advance; bvec->bv_len += advance; } - *bvprv = *bvec; } static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, Thanks, Ming From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 9 Jan 2018 22:33:41 +0800 From: Ming Lei To: Dmitry Osipenko Cc: Jens Axboe , Christoph Hellwig , Alexander Viro , Kent Overstreet , Huang Ying , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Theodore Ts'o , "Darrick J . Wong" , Coly Li , Filipe Manana , Ulf Hansson , linux-mmc@vger.kernel.org Subject: Re: [PATCH V4 13/45] block: blk-merge: try to make front segments in full size Message-ID: <20180109143339.GC4356@ming.t460p> References: <20171218122247.3488-1-ming.lei@redhat.com> <20171218122247.3488-14-ming.lei@redhat.com> <20180109023432.GB31067@ming.t460p> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: On Tue, Jan 09, 2018 at 04:18:39PM +0300, Dmitry Osipenko wrote: > On 09.01.2018 05:34, Ming Lei wrote: > > On Tue, Jan 09, 2018 at 12:09:27AM +0300, Dmitry Osipenko wrote: > >> On 18.12.2017 15:22, Ming Lei wrote: > >>> When merging one bvec into segment, if the bvec is too big > >>> to merge, current policy is to move the whole bvec into another > >>> new segment. > >>> > >>> This patchset changes the policy into trying to maximize size of > >>> front segments, that means in above situation, part of bvec > >>> is merged into current segment, and the remainder is put > >>> into next segment. > >>> > >>> This patch prepares for support multipage bvec because > >>> it can be quite common to see this case and we should try > >>> to make front segments in full size. > >>> > >>> Signed-off-by: Ming Lei > >>> --- > >>> block/blk-merge.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++----- > >>> 1 file changed, 49 insertions(+), 5 deletions(-) > >>> > >>> diff --git a/block/blk-merge.c b/block/blk-merge.c > >>> index a476337a8ff4..42ceb89bc566 100644 > >>> --- a/block/blk-merge.c > >>> +++ b/block/blk-merge.c > >>> @@ -109,6 +109,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>> bool do_split = true; > >>> struct bio *new = NULL; > >>> const unsigned max_sectors = get_max_io_size(q, bio); > >>> + unsigned advance = 0; > >>> > >>> bio_for_each_segment(bv, bio, iter) { > >>> /* > >>> @@ -134,12 +135,32 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>> } > >>> > >>> if (bvprvp && blk_queue_cluster(q)) { > >>> - if (seg_size + bv.bv_len > queue_max_segment_size(q)) > >>> - goto new_segment; > >>> if (!BIOVEC_PHYS_MERGEABLE(bvprvp, &bv)) > >>> goto new_segment; > >>> if (!BIOVEC_SEG_BOUNDARY(q, bvprvp, &bv)) > >>> goto new_segment; > >>> + if (seg_size + bv.bv_len > queue_max_segment_size(q)) { > >>> + /* > >>> + * On assumption is that initial value of > >>> + * @seg_size(equals to bv.bv_len) won't be > >>> + * bigger than max segment size, but will > >>> + * becomes false after multipage bvec comes. > >>> + */ > >>> + advance = queue_max_segment_size(q) - seg_size; > >>> + > >>> + if (advance > 0) { > >>> + seg_size += advance; > >>> + sectors += advance >> 9; > >>> + bv.bv_len -= advance; > >>> + bv.bv_offset += advance; > >>> + } > >>> + > >>> + /* > >>> + * Still need to put remainder of current > >>> + * bvec into a new segment. > >>> + */ > >>> + goto new_segment; > >>> + } > >>> > >>> seg_size += bv.bv_len; > >>> bvprv = bv; > >>> @@ -161,6 +182,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, > >>> seg_size = bv.bv_len; > >>> sectors += bv.bv_len >> 9; > >>> > >>> + /* restore the bvec for iterator */ > >>> + if (advance) { > >>> + bv.bv_len += advance; > >>> + bv.bv_offset -= advance; > >>> + advance = 0; > >>> + } > >>> } > >>> > >>> do_split = false; > >>> @@ -361,16 +388,29 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>> { > >>> > >>> int nbytes = bvec->bv_len; > >>> + unsigned advance = 0; > >>> > >>> if (*sg && *cluster) { > >>> - if ((*sg)->length + nbytes > queue_max_segment_size(q)) > >>> - goto new_segment; > >>> - > >>> if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) > >>> goto new_segment; > >>> if (!BIOVEC_SEG_BOUNDARY(q, bvprv, bvec)) > >>> goto new_segment; > >>> > >>> + /* > >>> + * try best to merge part of the bvec into previous > >>> + * segment and follow same policy with > >>> + * blk_bio_segment_split() > >>> + */ > >>> + if ((*sg)->length + nbytes > queue_max_segment_size(q)) { > >>> + advance = queue_max_segment_size(q) - (*sg)->length; > >>> + if (advance) { > >>> + (*sg)->length += advance; > >>> + bvec->bv_offset += advance; > >>> + bvec->bv_len -= advance; > >>> + } > >>> + goto new_segment; > >>> + } > >>> + > >>> (*sg)->length += nbytes; > >>> } else { > >>> new_segment: > >>> @@ -393,6 +433,10 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > >>> > >>> sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > >>> (*nsegs)++; > >>> + > >>> + /* for making iterator happy */ > >>> + bvec->bv_offset -= advance; > >>> + bvec->bv_len += advance; > >>> } > >>> *bvprv = *bvec; > >>> } > >>> > >> > >> Hello, > >> > >> This patch breaks MMC on next-20180108, in particular MMC doesn't work anymore > >> with this patch on NVIDIA Tegra20: > >> > >> <3>[ 36.622253] print_req_error: I/O error, dev mmcblk1, sector 512 > >> <3>[ 36.671233] print_req_error: I/O error, dev mmcblk2, sector 128 > >> <3>[ 36.711308] print_req_error: I/O error, dev mmcblk1, sector 31325304 > >> <3>[ 36.749232] print_req_error: I/O error, dev mmcblk2, sector 512 > >> <3>[ 36.761235] print_req_error: I/O error, dev mmcblk1, sector 31325816 > >> <3>[ 36.832039] print_req_error: I/O error, dev mmcblk2, sector 31259768 > >> <3>[ 99.793248] print_req_error: I/O error, dev mmcblk1, sector 31323136 > >> <3>[ 99.982043] print_req_error: I/O error, dev mmcblk1, sector 929792 > >> <3>[ 99.986301] print_req_error: I/O error, dev mmcblk1, sector 930816 > >> <3>[ 100.293624] print_req_error: I/O error, dev mmcblk1, sector 932864 > >> <3>[ 100.466839] print_req_error: I/O error, dev mmcblk1, sector 947200 > >> <3>[ 100.642955] print_req_error: I/O error, dev mmcblk1, sector 949248 > >> <3>[ 100.818838] print_req_error: I/O error, dev mmcblk1, sector 230400 > >> > >> Any attempt of mounting MMC block dev ends with a kernel crash. Reverting this > >> patch fixes the issue. > > > > Hi Dmitry, > > > > Thanks for your report! > > > > Could you share us what the segment limits are on your MMC? > > > > cat /sys/block/mmcN/queue/max_segment_size > > cat /sys/block/mmcN/queue/max_segments > > > > Please test the following patch to see if your issue can be fixed? > > > > --- > > diff --git a/block/blk-merge.c b/block/blk-merge.c > > index 446f63e076aa..cfab36c26608 100644 > > --- a/block/blk-merge.c > > +++ b/block/blk-merge.c > > @@ -431,12 +431,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, > > > > sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); > > (*nsegs)++; > > + } > > > > + *bvprv = *bvec; > > + if (advance) { > > /* for making iterator happy */ > > bvec->bv_offset -= advance; > > bvec->bv_len += advance; > > } > > - *bvprv = *bvec; > > } > > > > static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, > > Hi Ming, > > I've tried your patch and unfortunately it doesn't help with the issue. > > Here are the segment limits: > > # cat /sys/block/mmc*/queue/max_segment_size > 65535 Hi Dmitry, The 'max_segment_size' of 65535 should be the reason, could you test the following patch? --- diff --git a/block/blk-merge.c b/block/blk-merge.c index 446f63e076aa..38a66e3e678e 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -12,6 +12,8 @@ #include "blk.h" +#define sector_align(x) ALIGN_DOWN(x, 512) + static struct bio *blk_bio_discard_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, @@ -109,7 +111,7 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, bool do_split = true; struct bio *new = NULL; const unsigned max_sectors = get_max_io_size(q, bio); - unsigned advance = 0; + int advance = 0; bio_for_each_segment(bv, bio, iter) { /* @@ -144,8 +146,9 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, * bigger than max segment size, but this * becomes false after multipage bvecs. */ - advance = queue_max_segment_size(q) - seg_size; - + advance = sector_align( + queue_max_segment_size(q) - + seg_size); if (advance > 0) { seg_size += advance; sectors += advance >> 9; @@ -386,7 +389,7 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, { int nbytes = bvec->bv_len; - unsigned advance = 0; + int advance = 0; if (*sg && *cluster) { if (!BIOVEC_PHYS_MERGEABLE(bvprv, bvec)) @@ -400,8 +403,9 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, * blk_bio_segment_split() */ if ((*sg)->length + nbytes > queue_max_segment_size(q)) { - advance = queue_max_segment_size(q) - (*sg)->length; - if (advance) { + advance = sector_align(queue_max_segment_size(q) - + (*sg)->length); + if (advance > 0) { (*sg)->length += advance; bvec->bv_offset += advance; bvec->bv_len -= advance; @@ -431,12 +435,14 @@ __blk_segment_map_sg(struct request_queue *q, struct bio_vec *bvec, sg_set_page(*sg, bvec->bv_page, nbytes, bvec->bv_offset); (*nsegs)++; + } + *bvprv = *bvec; + if (advance > 0) { /* for making iterator happy */ bvec->bv_offset -= advance; bvec->bv_len += advance; } - *bvprv = *bvec; } static inline int __blk_bvec_map_sg(struct request_queue *q, struct bio_vec bv, Thanks, Ming -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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