Date: Mon, 5 May 2003 23:57:58 -0700
From: Andrew Morton <akpm@digeo.com>
To: "David S. Miller" <davem@redhat.com>
Cc: rusty@rustcorp.com.au, dipankar@in.ibm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kmalloc_percpu
Message-Id: <20030505235758.25f769fc.akpm@digeo.com>
In-Reply-To: <20030505.223944.23027730.davem@redhat.com>
References: <20030505.211606.28803580.davem@redhat.com>
	<20030505224815.07e5240c.akpm@digeo.com>
	<20030505234248.7cc05f43.akpm@digeo.com>
	<20030505.223944.23027730.davem@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1130
Lines: 28

"David S. Miller" <davem@redhat.com> wrote:
>
>    From: Andrew Morton <akpm@digeo.com>
>    Date: Mon, 5 May 2003 23:42:48 -0700
>    
>    Can't think of anything very clever there, except to go and un-percpuify the
>    disk stats.  I think that's best, really - disk requests only come in at 100
>    to 200 per second - atomic_t's or int-plus-per-disk-spinlock will be fine.
>    
> Use some spinlock we already have to be holding during the
> counter bumps.

Last time we looked at that, q->lock was already held in almost all the right
places so yes, that'd work.

> Frankly, these things don't need to be %100 accurate.  Using
> a new spinlock or an atomic_t for this seems rediculious.

The disk_stats structure has an "in flight" member.  If we don't have proper
locking around that, disks will appear to have -3 requests in flight for all
time, which would look a tad odd.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/