[Drbd-dev] [PATCH] - DRBD 8.0: Add standard disk counters to
DRBD devices
Lars Ellenberg
lars.ellenberg at linbit.com
Mon Apr 14 23:44:18 CEST 2008
On Mon, Apr 14, 2008 at 02:58:26PM -0400, Graham, Simon wrote:
> The attached patch adds support for the standard disk stats (as reported
> in /proc/diskstats et al) at the DRBD device level - this is nice
> because it can be used to show the actual response times etc at that
> level, after both local and remote (and meta data) I/O is done. These
> numbers also show up in the standard sar data for disk I/O.
wonderful :)
had been somewhere on my todo list for month,
never got around even to look at it, though.
thanks!
> It was a little trickier than I thought because getting the right values
> for the various time fields is not obvious but in the end I copied what
> md and ll_rw_blk.c do and the numbers certainly look correct now. There
> are also a few error paths at the top of make_request that do not count
> bio's that are failed early - since I need to hold the mdev request lock
> when manipulating the counters, I put the code in after the lock was
> already acquired which leaves a few error paths that are not counted.
> However, the normal paths are there, so I think it's OK.
that sounds perfectly reasonable.
Content-Description: 0003-Add-support-for-standard-disk-stats-to-DRBD-devices.patch
> From 0b35a81ccda06c6711cdf3cbae1a0cff033ca25e Mon Sep 17 00:00:00 2001
> From: Simon P. Graham <Simon.Graham at stratus.com>
> Date: Mon, 14 Apr 2008 10:35:33 -0400
> Subject: [PATCH] Add support for standard disk stats to DRBD devices
>
> ---
> drbd/drbd_int.h | 1 +
> drbd/drbd_req.c | 38 ++++++++++++++++++++++++++++++++++++++
> drbd/drbd_req.h | 1 +
> 3 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/drbd/drbd_int.h b/drbd/drbd_int.h
> index 8f693f3..05edc55 100644
> --- a/drbd/drbd_int.h
> +++ b/drbd/drbd_int.h
> @@ -629,6 +629,7 @@ struct drbd_request {
> struct bio *master_bio; /* master bio pointer */
> unsigned long rq_state; /* see comments above _req_mod() */
> int seq_num;
> + unsigned long start_time;
> };
yes, structures keep growing ...
somewhen we need to clean it all up again.
> struct drbd_barrier {
> diff --git a/drbd/drbd_req.c b/drbd/drbd_req.c
> index f06a0e4..d75b674 100644
> --- a/drbd/drbd_req.c
> +++ b/drbd/drbd_req.c
> @@ -105,6 +105,37 @@ void _print_req_mod(drbd_request_t *req,drbd_req_event_t what)
> #define print_req_mod(T,W)
> #endif
>
> +/* Update disk stats at start of I/O request */
> +static inline void _drbd_start_io_acct(drbd_dev *mdev, drbd_request_t *req, struct bio *bio)
> +{
> + int rw = bio_data_dir(bio);
> +
> + MUST_HOLD(&mdev->req_lock)
> +
> + disk_stat_inc(mdev->vdisk, ios[rw]);
> + disk_stat_add(mdev->vdisk, sectors[rw], bio_sectors(bio));
> + preempt_disable();
we are inside a spin_lock, no need to manipulate preempt,
there is no preemptible spin_lock yet.
> + disk_round_stats(mdev->vdisk);
> + preempt_enable();
> + mdev->vdisk->in_flight++;
> +}
> +
> +/* Update disk stats when completing request upwards */
> +static inline void _drbd_end_io_acct(drbd_dev *mdev, drbd_request_t *req)
> +{
> + int rw = bio_data_dir(req->master_bio);
> + unsigned long duration = jiffies - req->start_time;
> +
> + MUST_HOLD(&mdev->req_lock)
> +
> + preempt_disable();
same here.
> + disk_round_stats(mdev->vdisk);
> + preempt_enable();
> + mdev->vdisk->in_flight--;
> +
> + disk_stat_add(mdev->vdisk, ticks[rw], duration);
> +}
> +
> static void _req_is_done(drbd_dev *mdev, drbd_request_t *req, const int rw)
> {
> const unsigned long s = req->rq_state;
> @@ -335,6 +366,9 @@ void _req_may_be_done(drbd_request_t *req, int error)
> * then again, if it is a READ, it is not in the TL at all.
> * is it still leagal to complete a READ during freeze? */
>
> + /* Update disk stats */
> + _drbd_end_io_acct(mdev, req);
> +
> _complete_master_bio(mdev,req,
> ok ? 0 : ( error ? error : -EIO ) );
> } else {
> @@ -956,6 +990,9 @@ drbd_make_request_common(drbd_dev *mdev, struct bio *bio)
> }
>
>
> + /* Update disk stats */
> + _drbd_start_io_acct(mdev, req, bio);
> +
> /* _maybe_start_new_epoch(mdev);
> * If we need to generate a write barrier packet, we have to add the
> * new epoch (barrier) object, and queue the barrier packet for sending,
> @@ -1012,6 +1049,7 @@ drbd_make_request_common(drbd_dev *mdev, struct bio *bio)
> local = 0;
> }
> if (remote) dec_ap_pending(mdev);
> + _drbd_end_io_acct(mdev, req);
> /* THINK: do we want to fail it (-EIO), or pretend success? */
> bio_endio(req->master_bio, 0);
> req->master_bio = NULL;
> diff --git a/drbd/drbd_req.h b/drbd/drbd_req.h
> index 1d981b2..74d8dc1 100644
> --- a/drbd/drbd_req.h
> +++ b/drbd/drbd_req.h
> @@ -284,6 +284,7 @@ static inline drbd_request_t* drbd_req_new(drbd_dev *mdev, struct bio *bio_src)
> req->epoch = 0;
> req->sector = bio->bi_sector;
> req->size = bio->bi_size;
> + req->start_time = jiffies;
> INIT_HLIST_NODE(&req->colision);
> INIT_LIST_HEAD(&req->tl_requests);
>
> --
> 1.5.4-rc1.GIT
>
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--
: Lars Ellenberg Tel +43-1-8178292-55 :
: LINBIT Information Technologies GmbH Fax +43-1-8178292-82 :
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