Re: [patch 00/41] cpu alloc / cpu ops v3: Optimize per cpu access

Andrew Morton
2008-05-30T06:38:24Z

On Thu, 29 May 2008 23:22:31 -0700 (PDT) Christoph Lameter <clameter@sgi.com> wrote:

> On Thu, 29 May 2008, Andrew Morton wrote:
>
> > ext3 maintains three percpu_counters per mount. Each percpu_counter
> > does one percpu_alloc. People can mount an arbitrary number of ext3
> > filesystems!
>
> But its 4 bytes per alloc right?

It could be 4000. The present alloc_percpu() would support that.

And struct nfs_iostats is 264 bytes and nfs does an alloc_percpu() of
one of those per server and mounting thousands of servers per client
is, I believe, a real-world operation.

Plus for the entyenth time: saying that this code will probably work
acceptably for most people in 2.6.26 is not sufficient!