On Tue, Sep 06, 2011 at 12:08:51PM -0400, Mikulas Patocka wrote: > So, I can implement a call "void dm_bufio_discard_buffer(struct > dm_bufio_client *c, sector_t block)" and this call will discard a specific > buffer at a specific location (the call is not guaranteed to succeed, it > would not discard if someone is holding the buffer or so). It would be > like a "bforget" function for filesystem buffers. > > You will call this function on metadata sectors that you are freeing. > > Do you agree with this interface? That's not really what I was after, but it's a good idea. Don't do anything about it now, and I'll instrument to see if I can drive it effectively. I try and recycle freed blocks as quickly as possible to avoid fragmenting free space, which may mean there is little benefit. > Other than this, I don't know how to reduce cache size, I don't know about > any algorithm that would guess cache size automatically. In operating > systems, caches usually grow without limit regardless of whether someone > needs the cache or not. ok, let's go with things as they are. Thx for your hard work. One other optimisation to think about: As you know, if a non-blocking lookup of the thinp mapping fails, the bio gets handed across to a worker thread to do the blocking lookup. Is there any way to you could make dm_bm_read_try_lock() pass a preload hint to bufio, since we know that block is going to be required in the near future? - Joe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
