Re: VM issue causing high CPU loads

Yohan
2009-09-03T14:08:57Z

Trond Myklebust wrote:
> On Thu, 2009-09-03 at 15:39 +0200, Yohan wrote:
>
>>> As far as I can see, there is no RPCSEC_GSS involved, so credentials
>>> should never expire. They will be reused as long as processes aren't
>>> switching between thousands and thousands of different combinations of
>>> uid, gid and groups.
>>>
>> My servers are imap servers.
>> Foreach user (~15 million) it have a specific uid over ~10 nfs netapp
>> storage.
>>
> OK, so 16 hash buckets are likely to be filled with ~10^6 entries each.
> I can see that might be a performance issue...
>
> So afaics, you did try adjusting the hashtable size. How much larger
> does it have to be before you start to get acceptable performance? If it
> solves your problem we could make hash table sizes adjustable via a
> module parameter, for instance.
>
I run now with a value of 12, and it's great for me...