Messages in this thread | | | Date | Tue, 30 Jun 2015 18:25:36 -0700 | From | Jaegeuk Kim <> | Subject | Re: [PATCH 1/2] f2fs: refactor shrink flow for extent cache |
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Hi Chao,
On Tue, Jun 30, 2015 at 06:42:09PM +0800, Chao Yu wrote: > For now, in extent cache, we have a global lru list which links all extent > node in the cache, and the list is protected by a global spinlock. > > If we want to shrink extent cache, we will: > 1. delete all target extent node from global lru list under spinlock; > 2. traverse all per-inode extent tree in global radix tree; > 2.a. traverse all extent node in per-inode extent tree, try to free extent > node if it is not in global lru list already. > > This method is inefficient when there is huge number of inode extent tree in > global extent tree. > > In this patch we introduce a new method for extent cache shrinking: > When we attach a new extent node, we record extent tree pointer in extent node. > In shrink flow, we can try to find and lock extent tree of inode directly by > this backward pointer, and then detach the extent node from extent tree. > > This can help to shrink extent cache more efficiently.
Yes, but as we discussed before, this way will consume 4 bytes per each extent_node. Can it be acceptable?
Instead, IMO, we need to focus on how to increase its hit ratio first. Actually, I wrote a patch for that. Could you check that first?
Thanks,
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