lkml.org 
[lkml]   [2011]   [Jan]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [patch] fs: aio fix rcu lookup
From
On Thu, Jan 20, 2011 at 3:03 PM, Paul E. McKenney
<paulmck@linux.vnet.ibm.com> wrote:
> On Thu, Jan 20, 2011 at 08:20:00AM +1100, Nick Piggin wrote:
>> On Thu, Jan 20, 2011 at 8:03 AM, Jeff Moyer <jmoyer@redhat.com> wrote:
>> >> I don't know exactly how all programs use io_destroy -- of the small
>> >> number that do, probably an even smaller number would care here. But I
>> >> don't think it simplifies things enough to use synchronize_rcu for it.
>> >
>> > Above it sounded like you didn't think AIO should be using RCU at all.
>>
>> synchronize_rcu of course, not RCU (typo).
>
> I think that Nick is suggesting that call_rcu() be used instead.
> Perhaps also very sparing use of synchronize_rcu_expedited(), which
> is faster than synchronize_rcu(), but which which uses more CPU time.

call_rcu() is the obvious alternative, yes.

Basically, once we give in to synchronize_rcu() we're basically giving
up. That's certainly a very good tradeoff for something like filesystem
unregistration or module unload, it buys big simplifications in real
fastpaths. But I just don't think it should be taken lightly.


\
 
 \ /
  Last update: 2011-01-20 19:35    [W:0.086 / U:2.140 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site