On 01/14/2018 03:42 PM, Coly Li wrote:
> From: Tang Junhui <tang.junhui@xxxxxxxxxx>
>
> When we run IO in a detached device, and run iostat to shows IO status,
> normally it will show like bellow (Omitted some fields):
> Device: ... avgrq-sz avgqu-sz await r_await w_await svctm %util
> sdd ... 15.89 0.53 1.82 0.20 2.23 1.81 52.30
> bcache0 ... 15.89 115.42 0.00 0.00 0.00 2.40 69.60
> but after IO stopped, there are still very big avgqu-sz and %util
> values as bellow:
> Device: ... avgrq-sz avgqu-sz await r_await w_await svctm %util
> bcache0 ... 0 5326.32 0.00 0.00 0.00 0.00 100.10
>
> The reason for this issue is that, only generic_start_io_acct() called
> and no generic_end_io_acct() called for detached device in
> cached_dev_make_request(). See the code:
> //start generic_start_io_acct()
> generic_start_io_acct(q, rw, bio_sectors(bio), &d->disk->part0);
> if (cached_dev_get(dc)) {
> //will callback generic_end_io_acct()
> }
> else {
> //will not call generic_end_io_acct()
> }
>
> This patch calls generic_end_io_acct() in the end of IO for detached
> devices, so we can show IO state correctly.
>
> (Modified to use GFP_NOIO in kzalloc() by Coly Li)
>
> Signed-off-by: Tang Junhui <tang.junhui@xxxxxxxxxx>
> Reviewed-by: Coly Li <colyli@xxxxxxx>
> ---
> drivers/md/bcache/request.c | 58 +++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 51 insertions(+), 7 deletions(-)
>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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