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Message-Id: <20090918110026.2251.A69D9226@jp.fujitsu.com>
Date: Fri, 18 Sep 2009 11:02:50 +0900 (JST)
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: "Jun'ichi Nomura" <j-nomura@...jp.nec.com>
Cc: kosaki.motohiro@...fujitsu.com, linux-kernel@...r.kernel.org,
device-mapper development <dm-devel@...hat.com>,
Jens Axboe <jens.axboe@...cle.com>,
Alasdair G Kergon <agk@...hat.com>,
Li Zefan <lizf@...fujitsu.com>
Subject: Re: [PATCH] Add a tracepoint for block request remapping
CC to Li
Li, What do you think?
> Since 2.6.31 now has request-based device-mapper, it's useful to have
> a tracepoint for request-remapping as well as bio-remapping.
>
> This patch adds a tracepoint for request-remapping, trace_block_rq_remap().
> Existing trace_block_remap() is left unchanged but it might be better to
> rename it to trace_block_bio_remap().
>
> Signed-off-by: Kiyoshi Ueda <k-ueda@...jp.nec.com>
> Signed-off-by: Jun'ichi Nomura <j-nomura@...jp.nec.com>
> Cc: Jens Axboe <jens.axboe@...cle.com>
> Cc: Alasdair G Kergon <agk@...hat.com>
> ---
> block/blk-core.c | 11 +++++-----
> drivers/md/dm.c | 6 +++--
> include/trace/events/block.h | 35 +++++++++++++++++++++++++++++++++-
> kernel/trace/blktrace.c | 44 ++++++++++++++++++++++++++++++++++++++-----
> 4 files changed, 83 insertions(+), 13 deletions(-)
>
> Index: linux-2.6.31/block/blk-core.c
> ===================================================================
> --- linux-2.6.31.orig/block/blk-core.c
> +++ linux-2.6.31/block/blk-core.c
> @@ -34,6 +34,7 @@
> #include "blk.h"
>
> EXPORT_TRACEPOINT_SYMBOL_GPL(block_remap);
> +EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
> EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
>
> static int __make_request(struct request_queue *q, struct bio *bio);
> Index: linux-2.6.31/drivers/md/dm.c
> ===================================================================
> --- linux-2.6.31.orig/drivers/md/dm.c
> +++ linux-2.6.31/drivers/md/dm.c
> @@ -1503,6 +1503,8 @@ static void map_request(struct dm_target
> break;
> case DM_MAPIO_REMAPPED:
> /* The target has remapped the I/O so dispatch it */
> + trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
> + blk_rq_pos(tio->orig));
> dm_dispatch_request(clone);
> break;
> case DM_MAPIO_REQUEUE:
> Index: linux-2.6.31/include/trace/events/block.h
> ===================================================================
> --- linux-2.6.31.orig/include/trace/events/block.h
> +++ linux-2.6.31/include/trace/events/block.h
> @@ -486,6 +486,39 @@ TRACE_EVENT(block_remap,
> (unsigned long long)__entry->old_sector)
> );
>
> +TRACE_EVENT(block_rq_remap,
> +
> + TP_PROTO(struct request_queue *q, struct request *rq, dev_t dev,
> + sector_t from),
> +
> + TP_ARGS(q, rq, dev, from),
> +
> + TP_STRUCT__entry(
> + __field( dev_t, dev )
> + __field( sector_t, sector )
> + __field( unsigned int, nr_sector )
> + __field( dev_t, old_dev )
> + __field( sector_t, old_sector )
> + __array( char, rwbs, 6 )
> + ),
> +
> + TP_fast_assign(
> + __entry->dev = disk_devt(rq->rq_disk);
> + __entry->sector = blk_rq_pos(rq);
> + __entry->nr_sector = blk_rq_sectors(rq);
> + __entry->old_dev = dev;
> + __entry->old_sector = from;
> + blk_fill_rwbs_rq(__entry->rwbs, rq);
> + ),
> +
> + TP_printk("%d,%d %s %llu + %u <- (%d,%d) %llu",
> + MAJOR(__entry->dev), MINOR(__entry->dev), __entry->rwbs,
> + (unsigned long long)__entry->sector,
> + __entry->nr_sector,
> + MAJOR(__entry->old_dev), MINOR(__entry->old_dev),
> + (unsigned long long)__entry->old_sector)
> +);
> +
> #endif /* _TRACE_BLOCK_H */
>
> /* This part must be outside protection */
> Index: linux-2.6.31/kernel/trace/blktrace.c
> ===================================================================
> --- linux-2.6.31.orig/kernel/trace/blktrace.c
> +++ linux-2.6.31/kernel/trace/blktrace.c
> @@ -852,6 +852,37 @@ static void blk_add_trace_remap(struct r
> }
>
> /**
> + * blk_add_trace_rq_remap - Add a trace for a request-remap operation
> + * @q: queue the io is for
> + * @rq: the source request
> + * @dev: target device
> + * @from: source sector
> + *
> + * Description:
> + * Device mapper remaps request to other devices.
> + * Add a trace for that action.
> + *
> + **/
> +static void blk_add_trace_rq_remap(struct request_queue *q,
> + struct request *rq, dev_t dev,
> + sector_t from)
> +{
> + struct blk_trace *bt = q->blk_trace;
> + struct blk_io_trace_remap r;
> +
> + if (likely(!bt))
> + return;
> +
> + r.device_from = cpu_to_be32(dev);
> + r.device_to = disk_devt(rq->rq_disk);
> + r.sector_from = cpu_to_be64(from);
> +
> + __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
> + rq_data_dir(rq), BLK_TA_REMAP, !!rq->errors,
> + sizeof(r), &r);
> +}
> +
> +/**
> * blk_add_driver_data - Add binary message with driver-specific data
> * @q: queue the io is for
> * @rq: io request
> @@ -918,10 +949,13 @@ static void blk_register_tracepoints(voi
> WARN_ON(ret);
> ret = register_trace_block_remap(blk_add_trace_remap);
> WARN_ON(ret);
> + ret = register_trace_block_rq_remap(blk_add_trace_rq_remap);
> + WARN_ON(ret);
> }
>
> static void blk_unregister_tracepoints(void)
> {
> + unregister_trace_block_rq_remap(blk_add_trace_rq_remap);
> unregister_trace_block_remap(blk_add_trace_remap);
> unregister_trace_block_split(blk_add_trace_split);
> unregister_trace_block_unplug_io(blk_add_trace_unplug_io);
> --
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