Messages in this thread | | | From | Guoqing Jiang <> | Subject | Re: [PATCH v3 5/5] md/raid10: convert resync_lock to use seqlock | Date | Mon, 19 Sep 2022 18:28:29 +0800 |
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On 9/19/22 9:08 AM, Yu Kuai wrote: > Hi, > > 在 2022/09/18 19:36, Guoqing Jiang 写道: >> >> >> On 9/16/22 7:34 PM, Yu Kuai wrote: >>> From: Yu Kuai <yukuai3@huawei.com> >>> >>> Currently, wait_barrier() will hold 'resync_lock' to read >>> 'conf->barrier', >>> and io can't be dispatched until 'barrier' is dropped. >>> >>> Since holding the 'barrier' is not common, convert 'resync_lock' to use >>> seqlock so that holding lock can be avoided in fast path. >>> >>> Signed-off-by: Yu Kuai <yukuai3@huawei.com> >>> --- >>> drivers/md/raid10.c | 87 >>> ++++++++++++++++++++++++++++++--------------- >>> drivers/md/raid10.h | 2 +- >>> 2 files changed, 59 insertions(+), 30 deletions(-) >>> >>> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c >>> index 9a28abd19709..2daa7d57034c 100644 >>> --- a/drivers/md/raid10.c >>> +++ b/drivers/md/raid10.c >>> @@ -79,6 +79,21 @@ static void end_reshape(struct r10conf *conf); >>> #include "raid1-10.c" >>> +#define NULL_CMD >>> +#define cmd_before(conf, cmd) \ >>> + do { \ >>> + write_sequnlock_irq(&(conf)->resync_lock); \ >>> + cmd; \ >>> + } while (0) >>> +#define cmd_after(conf) write_seqlock_irq(&(conf)->resync_lock) >> >> The two is not paired well given only cmd_before needs the 'cmd'. > > May be should I just remove cmd_after?
I'd remove it but just my personal flavor.
>> >>> + >>> +#define wait_event_barrier_cmd(conf, cond, cmd) \ >>> + wait_event_cmd((conf)->wait_barrier, cond, cmd_before(conf, >>> cmd), \ >>> + cmd_after(conf)) >>> + >>> +#define wait_event_barrier(conf, cond) \ >>> + wait_event_barrier_cmd(conf, cond, NULL_CMD) >> >> What is the issue without define NULL_CMD? >> > > Checkpatch will complain this: > > ERROR: space prohibited before that close parenthesis ')' > #38: FILE: drivers/md/raid10.c:94: > + wait_event_barrier_cmd(conf, cond, ) > > total: 1 errors, 0 warnings, 169 lines checked
Hmm, freeze_array has a different usage for it, so two cmds before sleep and one cmd after sleep, perhaps it is the best way for now.
Thanks, Guoqing
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