From: Dennis Zhou <[email protected]>
To: Tejun Heo <[email protected]>
Cc: Jens Axboe <[email protected]>,
Pavel Begunkov <[email protected]>,
[email protected], [email protected],
Dennis Zhou <[email protected]>, Christoph Lameter <[email protected]>
Subject: Re: [PATCH 1/2] pcpu_ref: add percpu_ref_tryget_many()
Date: Wed, 18 Dec 2019 11:49:55 -0600 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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?
>
> 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.
> >
> >
> > 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
next prev parent reply other threads:[~2019-12-18 17:50 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 [this message]
2019-12-21 15:36 ` Pavel Begunkov
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191218174955.GA14991@dennisz-mbp.dhcp.thefacebook.com \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
[email protected] \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox