From: Andrew Morton <akpm@linux-foundation.org>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Elena Reshetova <elena.reshetova@intel.com>,
linux-kernel@vger.kernel.org, peterz@infradead.org,
gregkh@linuxfoundation.org, mingo@redhat.com,
adobriyan@gmail.com, serge@hallyn.com, arozansk@redhat.com,
keescook@chromium.org, Hans Liljestrand <ishkamiel@gmail.com>,
David Windsor <dwindsor@gmail.com>
Subject: Re: [PATCH 1/3] ipc: convert ipc_namespace.count from atomic_t to refcount_t
Date: Wed, 19 Jul 2017 15:58:33 -0700 [thread overview]
Message-ID: <20170719155833.641a283467bf6b89a7d2e56b@linux-foundation.org> (raw)
In-Reply-To: <20170719225427.GD14395@linux-80c1.suse>
On Wed, 19 Jul 2017 15:54:27 -0700 Davidlohr Bueso <dave@stgolabs.net> wrote:
> On Wed, 19 Jul 2017, Andrew Morton wrote:
>
> >I do rather dislike these conversions from the point of view of
> >performance overhead and general code bloat. But I seem to have lost
> >that struggle and I don't think any of these are fastpath(?).
>
> Well, since we now have fd25d19 (locking/refcount: Create unchecked atomic_t
> implementation), performance is supposed to be ok.
Sure, things are OK for people who disable the feature.
But for people who want to enable the feature we really should minimize
the cost by avoiding blindly converting sites which simply don't need
it: simple, safe, old, well-tested code. Why go and slow down such
code? Need to apply some common sense here...
> It would be lovely to have
> some actual numbers nonetheless.
Very much so.
next prev parent reply other threads:[~2017-07-19 22:58 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-07 8:59 [PATCH 0/3] v2 ipc subsystem refcount coversions Elena Reshetova
2017-07-07 8:59 ` [PATCH 1/3] ipc: convert ipc_namespace.count from atomic_t to refcount_t Elena Reshetova
2017-07-09 21:59 ` Eric W. Biederman
2017-07-10 6:48 ` Reshetova, Elena
2017-07-10 8:37 ` Eric W. Biederman
2017-07-10 9:34 ` Alexey Dobriyan
2017-07-10 11:19 ` Eric W. Biederman
2017-07-10 9:56 ` Reshetova, Elena
2017-07-10 11:26 ` Eric W. Biederman
2017-07-10 12:11 ` Reshetova, Elena
2017-07-10 20:32 ` Eric W. Biederman
2017-07-12 9:21 ` Reshetova, Elena
2017-07-19 22:35 ` Andrew Morton
2017-07-19 22:54 ` Davidlohr Bueso
2017-07-19 22:58 ` Andrew Morton [this message]
2017-07-19 23:11 ` Davidlohr Bueso
2017-07-19 23:20 ` Kees Cook
2017-07-20 0:32 ` Kees Cook
2017-07-20 9:34 ` Ingo Molnar
2017-07-20 12:34 ` Eric W. Biederman
2017-07-20 15:12 ` Kees Cook
2017-07-07 8:59 ` [PATCH 2/3] ipc: convert sem_undo_list.refcnt " Elena Reshetova
2017-07-07 8:59 ` [PATCH 3/3] ipc: convert kern_ipc_perm.refcount " Elena Reshetova
-- strict thread matches above, loose matches on Subject: below --
2017-02-20 11:29 [PATCH 0/3] ipc subsystem refcounter conversions Elena Reshetova
2017-02-20 11:29 ` [PATCH 1/3] ipc: convert ipc_namespace.count from atomic_t to refcount_t Elena Reshetova
2017-05-27 19:41 ` Kees Cook
2017-05-28 12:10 ` Manfred Spraul
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