From: Pavel Begunkov <[email protected]>
To: Dennis Zhou <[email protected]>, Tejun Heo <[email protected]>
Cc: Jens Axboe <[email protected]>,
[email protected], [email protected],
Christoph Lameter <[email protected]>
Subject: Re: [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many()
Date: Sat, 21 Dec 2019 18:36:32 +0300 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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On 18/12/2019 20:49, Dennis Zhou wrote:
> On Wed, Dec 18, 2019 at 08:26:42AM -0800, Tejun Heo wrote:
>> (cc'ing Dennis and Christoph and quoting whole body)
>>
>> Pavel, can you please cc percpu maintainers on related changes?
My bad, lost cc's in the way.
>>
>> The patch looks fine to me. Please feel free to add my acked-by.
>>
>> On Tue, Dec 17, 2019 at 04:42:59PM -0700, Jens Axboe wrote:
>>> CC Tejun on this one. Looks fine to me, and matches the put path.
Thanks both for taking a look!
>>>
>>>
>>> On 12/17/19 3:28 PM, Pavel Begunkov wrote:
>>>> Add percpu_ref_tryget_many(), which works the same way as
>>>> percpu_ref_tryget(), but grabs specified number of refs.
>>>>
>>>> Signed-off-by: Pavel Begunkov <[email protected]>
>>>> ---
>>>> include/linux/percpu-refcount.h | 24 ++++++++++++++++++++----
>>>> 1 file changed, 20 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/include/linux/percpu-refcount.h b/include/linux/percpu-refcount.h
>>>> index 390031e816dc..19079b62ce31 100644
>>>> --- a/include/linux/percpu-refcount.h
>>>> +++ b/include/linux/percpu-refcount.h
>>>> @@ -210,15 +210,17 @@ static inline void percpu_ref_get(struct percpu_ref *ref)
>>>> }
>>>>
>>>> /**
>>>> - * percpu_ref_tryget - try to increment a percpu refcount
>>>> + * percpu_ref_tryget_many - try to increment a percpu refcount
>>>> * @ref: percpu_ref to try-get
>>>> + * @nr: number of references to get
>>>> *
>>>> * Increment a percpu refcount unless its count already reached zero.
>>>> * Returns %true on success; %false on failure.
>
> Minor nit: would be nice to change this so the two don't have identical
> comments. (eg: Increment a percpu refcount by @nr unless...)
>>>> *
>>>> * This function is safe to call as long as @ref is between init and exit.
>>>> */
>>>> -static inline bool percpu_ref_tryget(struct percpu_ref *ref)
>>>> +static inline bool percpu_ref_tryget_many(struct percpu_ref *ref,
>>>> + unsigned long nr)
>>>> {
>>>> unsigned long __percpu *percpu_count;
>>>> bool ret;
>>>> @@ -226,10 +228,10 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
>>>> rcu_read_lock();
>>>>
>>>> if (__ref_is_percpu(ref, &percpu_count)) {
>>>> - this_cpu_inc(*percpu_count);
>>>> + this_cpu_add(*percpu_count, nr);
>>>> ret = true;
>>>> } else {
>>>> - ret = atomic_long_inc_not_zero(&ref->count);
>>>> + ret = atomic_long_add_unless(&ref->count, nr, 0);
>>>> }
>>>>
>>>> rcu_read_unlock();
>>>> @@ -237,6 +239,20 @@ static inline bool percpu_ref_tryget(struct percpu_ref *ref)
>>>> return ret;
>>>> }
>>>>
>>>> +/**
>>>> + * percpu_ref_tryget - try to increment a percpu refcount
>>>> + * @ref: percpu_ref to try-get
>>>> + *
>>>> + * Increment a percpu refcount unless its count already reached zero.
>>>> + * Returns %true on success; %false on failure.
>>>> + *
>>>> + * This function is safe to call as long as @ref is between init and exit.
>>>> + */
>>>> +static inline bool percpu_ref_tryget(struct percpu_ref *ref)
>>>> +{
>>>> + return percpu_ref_tryget_many(ref, 1);
>>>> +}
>>>> +
>>>> /**
>>>> * percpu_ref_tryget_live - try to increment a live percpu refcount
>>>> * @ref: percpu_ref to try-get
>>>>
>>>
>>>
>>> --
>>> Jens Axboe
>>>
>>
>> --
>> tejun
>
> Acked-by: Dennis Zhou <[email protected]>
>
> Thanks,
> Dennis
>
--
Pavel Begunkov
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next prev parent reply other threads:[~2019-12-21 15:37 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-17 22:28 [PATCH 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-17 22:28 ` [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-17 23:42 ` Jens Axboe
2019-12-18 16:26 ` Tejun Heo
2019-12-18 17:49 ` Dennis Zhou
2019-12-21 15:36 ` Pavel Begunkov [this message]
2019-12-17 22:28 ` [PATCH 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-17 23:21 ` Jens Axboe
2019-12-17 23:31 ` Jens Axboe
2019-12-18 9:25 ` Pavel Begunkov
2019-12-18 9:23 ` Pavel Begunkov
2019-12-18 0:02 ` Jens Axboe
2019-12-18 10:41 ` Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 0/3] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 1/3] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 16:15 ` [PATCH v2 2/3] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 16:15 ` [PATCH RFC v2 3/3] io_uring: batch get(ctx->ref) across submits Pavel Begunkov
2019-12-21 16:20 ` Pavel Begunkov
2019-12-21 16:38 ` Jens Axboe
2019-12-21 16:48 ` Pavel Begunkov
2019-12-21 17:01 ` Jens Axboe
2019-12-21 17:26 ` Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-21 20:12 ` [PATCH v3 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-21 21:56 ` Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 0/2] optimise ctx's refs grabbing in io_uring Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 1/2] pcpu_ref: add percpu_ref_tryget_many() Pavel Begunkov
2019-12-28 11:13 ` [PATCH v4 2/2] io_uring: batch getting pcpu references Pavel Begunkov
2019-12-28 11:15 ` Pavel Begunkov
2019-12-28 17:03 ` Jens Axboe
2019-12-28 18:37 ` Pavel Begunkov
2019-12-30 3:33 ` Brian Gianforcaro
2019-12-30 18:45 ` Pavel Begunkov
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