From: Peter Zijlstra <peterz@infradead.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>,
David Rientjes <rientjes@google.com>,
Lee Schermerhorn <lee.schermerhorn@hp.com>,
Paul Menage <menage@google.com>,
Linux-Kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>, tglx <tglx@linutronix.de>
Subject: Re: [PATCH 4/4] cpuset,mm: use rwlock to protect task->mempolicy and mems_allowed
Date: Thu, 04 Mar 2010 15:58:24 +0100 [thread overview]
Message-ID: <1267714704.25158.199.camel@laptop> (raw)
In-Reply-To: <20100304033017.GN8653@laptop>
On Thu, 2010-03-04 at 14:30 +1100, Nick Piggin wrote:
>
> Thanks for working on this. However, rwlocks are pretty nasty to use
> when you have short critical sections and hot read-side (they're twice
> as heavy as even spinlocks in that case).
Should we add a checkpatch.pl warning for them?
There really rarely is a good case for using rwlock_t, for as you say
they're a pain and often more expensive than a spinlock_t, and if
possible RCU has the best performance.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Miao Xie <miaox@cn.fujitsu.com>,
David Rientjes <rientjes@google.com>,
Lee Schermerhorn <lee.schermerhorn@hp.com>,
Paul Menage <menage@google.com>,
Linux-Kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>, tglx <tglx@linutronix.de>
Subject: Re: [PATCH 4/4] cpuset,mm: use rwlock to protect task->mempolicy and mems_allowed
Date: Thu, 04 Mar 2010 15:58:24 +0100 [thread overview]
Message-ID: <1267714704.25158.199.camel@laptop> (raw)
In-Reply-To: <20100304033017.GN8653@laptop>
On Thu, 2010-03-04 at 14:30 +1100, Nick Piggin wrote:
>
> Thanks for working on this. However, rwlocks are pretty nasty to use
> when you have short critical sections and hot read-side (they're twice
> as heavy as even spinlocks in that case).
Should we add a checkpatch.pl warning for them?
There really rarely is a good case for using rwlock_t, for as you say
they're a pain and often more expensive than a spinlock_t, and if
possible RCU has the best performance.
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next prev parent reply other threads:[~2010-03-04 14:58 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-03 10:52 [PATCH 4/4] cpuset,mm: use rwlock to protect task->mempolicy and mems_allowed Miao Xie
2010-03-03 10:52 ` Miao Xie
2010-03-03 23:50 ` Andrew Morton
2010-03-03 23:50 ` Andrew Morton
2010-03-04 9:03 ` Miao Xie
2010-03-04 9:03 ` Miao Xie
2010-03-04 3:30 ` Nick Piggin
2010-03-04 3:30 ` Nick Piggin
2010-03-04 9:36 ` Miao Xie
2010-03-04 9:36 ` Miao Xie
2010-03-04 14:58 ` Peter Zijlstra [this message]
2010-03-04 14:58 ` Peter Zijlstra
2010-03-04 16:34 ` Nick Piggin
2010-03-04 16:34 ` Nick Piggin
2010-03-04 4:53 ` Nick Piggin
2010-03-04 4:53 ` Nick Piggin
2010-03-04 14:31 ` Lee Schermerhorn
2010-03-04 14:31 ` Lee Schermerhorn
2010-03-05 13:05 ` Lee Schermerhorn
2010-03-05 13:05 ` Lee Schermerhorn
2010-03-05 12:03 ` Paul Menage
2010-03-05 12:03 ` Paul Menage
2010-03-07 2:33 ` Miao Xie
2010-03-07 2:33 ` Miao Xie
2010-03-09 19:42 ` Paul Menage
2010-03-09 19:42 ` Paul Menage
2010-03-11 5:04 ` Miao Xie
2010-03-11 5:04 ` Miao Xie
2010-03-11 5:30 ` Nick Piggin
2010-03-11 5:30 ` Nick Piggin
2010-03-11 7:57 ` Miao Xie
2010-03-11 7:57 ` Miao Xie
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