Re: [PATCH] kmalloc_percpu

[Andrew Morton]

"David S. Miller" <[e-mail]> wrote:
>
>    From: Andrew Morton <[e-mail]>
>    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.