Re: [PATCH] Radix-tree pagecache for 2.5

[Momchil Velikov]

>>>>> "Ingo" == Ingo Molnar <[e-mail]> writes:

Ingo> On 1 Feb 2002, Momchil Velikov wrote:

Ingo> files are used. With one big file (or a few big files), the i_shared_lock
Ingo> will always bounce between CPUs wildly in read() workloads, degrading
>> 
>> Will there be difference between bounces of a rwlock in the radix tree
>> variant and the cache misses in hashed locks variant for the case of
>> concurrently accessed large file ?

Ingo> definitely, because in the case of page buckets there are many locks
Ingo> hashed in a mapping-neutral way. Ie. different parts of the same file will
Ingo> likely map to different spinlocks.

That's why it's likely to miss on each access.  

Ingo> In the radix tree case all pages in the inode will map to the
Ingo> same spinlock.

That's why it's likely to bounce on each access.

So, is there any difference ? :)

Regards,
-velco