On Tue, Oct 09, 2012 at 02:53:45PM +0800, Robin Dong wrote:
> From: Robin Dong <san...@taobao.com>
>
> Currently, if the IO is throttled by io-throttle, the SA has no idea of
> the situation and can't report it to the real application user about
> that he/she has to do something. So this patch adds a new interface
> named blkio.throttle.io_queued which indicates how many IOs are
> currently throttled.
>
> The nr_queued[] of struct throtl_grp is of type "unsigned int" and updates
> to it are atomic both at 32bit and 64bit platforms, so we could just
> read tg->nr_queued only under blkcg->lock.
>
> Changelog from v2:
> Use nr-queued[] of struct throtl_grp for stats instaed of adding new
> blkg_rwstat.
>
> Cc: Tejun Heo <t...@kernel.org>
> Cc: Vivek Goyal <vgo...@redhat.com>
> Cc: Jens Axboe <ax...@kernel.dk>
> Signed-off-by: Tao Ma <boyu...@taobao.com>
> Signed-off-by: Robin Dong <san...@taobao.com>
> ---
> block/blk-throttle.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 40 insertions(+), 0 deletions(-)
>
> diff --git a/block/blk-throttle.c b/block/blk-throttle.c
> index a9664fa..e410448 100644
> --- a/block/blk-throttle.c
> +++ b/block/blk-throttle.c
> @@ -953,6 +953,32 @@ static u64 tg_prfill_cpu_rwstat(struct seq_file *sf,
> return __blkg_prfill_rwstat(sf, pd, &rwstat);
> }
>
> +static u64 tg_prfill_io_queued(struct seq_file *sf,
> + struct blkg_policy_data *pd, int off)
> +{
> + static const char *rwstr[] = {
> + [READ] = "Read",
> + [WRITE] = "Write",
> + };
> + struct throtl_grp *tg = pd_to_tg(pd);
> + const char *dname = NULL;
> + unsigned int v;
> + int i;
> +
> + if (pd->blkg->q->backing_dev_info.dev)
> + dname = dev_name(pd->blkg->q->backing_dev_info.dev);
> +
> + if (!dname)
> + return 0;
> +
> + for (i = 0; i <= WRITE; i++)
> + seq_printf(sf, "%s %s %u\n", dname, rwstr[i], tg->nr_queued[i]);
You are printing only READ/WRITE stats and not the SYNC/ASYNC stats. This
is not inline with rest of the stats like throttle.io_serviced and
throttle.io_service_bytes.
I guess it is better to maintain rwstat for io_queued and display it
according to io_serviced.
Thanks
Vivek
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