From: Andrew Morton <akpm@osdl•org>
To: Ravikiran G Thirumalai <kiran@scalex86•org>
Cc: bcrl@kvack•org, linux-kernel@vger•kernel.org,
davem@davemloft•net, netdev@vger•kernel.org, shai@scalex86•org
Subject: Re: [patch 1/4] net: percpufy frequently used vars -- add percpu_counter_mod_bh
Date: Wed, 8 Mar 2006 16:32:58 -0800 [thread overview]
Message-ID: <20060308163258.36f3bd79.akpm@osdl.org> (raw)
In-Reply-To: <20060309001803.GF4493@localhost.localdomain>
Ravikiran G Thirumalai <kiran@scalex86•org> wrote:
>
> On Wed, Mar 08, 2006 at 03:43:21PM -0800, Andrew Morton wrote:
> > Benjamin LaHaise <bcrl@kvack•org> wrote:
> > >
> > > I think it may make more sense to simply convert local_t into a long, given
> > > that most of the users will be things like stats counters.
> > >
> >
> > Yes, I agree that making local_t signed would be better. It's consistent
> > with atomic_t, atomic64_t and atomic_long_t and it's a bit more flexible.
> >
> > Perhaps. A lot of applications would just be upcounters for statistics,
> > where unsigned is desired. But I think the consistency argument wins out.
>
> It already is... for most of the arches except x86_64.
x86 uses unsigned long.
> And on -mm, the asm-generic version uses atomic_long_t for local_t (signed
> long) which seems right.
No, it uses unsigned long. The only place where signedness matters is
local_read(), and there it is typecast to ulong.
> Although, I wonder why we use:
>
> #define local_read(l) ((unsigned long)atomic_long_read(&(l)->a))
>
> It would return a huge value if the local counter was even -1 no?
It's casting a signed long to an unsigned long. That does the right thing.
Yes, it'll convert -1 to 0xffffffff[ffffffff].
next prev parent reply other threads:[~2006-03-09 0:32 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-08 1:58 [patch 0/4] net: percpufy frequently used vars on struct proto Ravikiran G Thirumalai
2006-03-08 1:59 ` [patch 1/4] net: percpufy frequently used vars -- add percpu_counter_mod_bh Ravikiran G Thirumalai
2006-03-08 2:13 ` Andrew Morton
2006-03-08 20:26 ` Ravikiran G Thirumalai
2006-03-08 20:36 ` Benjamin LaHaise
2006-03-08 21:07 ` Ravikiran G Thirumalai
2006-03-08 21:17 ` Benjamin LaHaise
2006-03-08 22:25 ` Ravikiran G Thirumalai
2006-03-08 22:41 ` Benjamin LaHaise
2006-03-08 23:43 ` Andrew Morton
2006-03-09 0:18 ` Ravikiran G Thirumalai
2006-03-09 0:32 ` Andrew Morton [this message]
2006-03-09 8:06 ` Ravikiran G Thirumalai
2006-03-09 4:14 ` Andi Kleen
2006-03-09 8:14 ` Nick Piggin
2006-03-09 8:22 ` Ravikiran G Thirumalai
2006-03-09 8:41 ` Nick Piggin
2006-03-09 18:39 ` Benjamin LaHaise
2006-03-08 23:06 ` Andrew Morton
2006-03-08 23:12 ` Andrew Morton
2006-03-09 2:21 ` Andi Kleen
2006-03-09 2:32 ` Andrew Morton
2006-03-08 2:01 ` [patch 2/4] net: percpufy frequently used vars -- struct proto.memory_allocated Ravikiran G Thirumalai
2006-03-08 2:14 ` Andrew Morton
2006-03-08 3:08 ` Ravikiran G Thirumalai
2006-03-08 3:22 ` Andrew Morton
2006-03-08 20:54 ` Ravikiran G Thirumalai
2006-03-08 2:02 ` [patch 3/4] net: percpufy frequently used vars -- proto.sockets_allocated Ravikiran G Thirumalai
2006-03-08 2:16 ` Andrew Morton
2006-03-08 20:56 ` Ravikiran G Thirumalai
2006-03-08 2:03 ` [patch 4/4] net: percpufy frequently used vars -- proto.inuse Ravikiran G Thirumalai
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