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

[Christoph Lameter]

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?

> Another: there are two percpu_counters (and hence two percpu_alloc()s)
> per backing_dev_info.  One backing_dev_info per disk and people have
> been known to have thousands (iirc ~10,000) disks online.

8 bytes per backing device. 80000 bytes for 10000 disks.

> And those examples were plucked only from today's kernel.  Who knows
> what other problems will be in 2.6.45?

We can always increase the sizes.
 
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