Messages in this thread | | | Date | Mon, 17 Aug 2009 10:38:28 +0530 | From | Nitin Gupta <> | Subject | Re: [PATCH] swap: send callback when swap slot is freed |
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On 08/17/2009 08:25 AM, KAMEZAWA Hiroyuki wrote: > On Wed, 12 Aug 2009 20:07:43 +0530 > Nitin Gupta<ngupta@vflare.org> wrote: > >> Currently, we have "swap discard" mechanism which sends a discard bio request >> when we find a free cluster during scan_swap_map(). This callback can come a >> long time after swap slots are actually freed. >> >> This delay in callback is a great problem when (compressed) RAM [1] is used >> as a swap device. So, this change adds a callback which is called as >> soon as a swap slot becomes free. For above mentioned case of swapping >> over compressed RAM device, this is very useful since we can immediately >> free memory allocated for this swap page. >> >> This callback does not replace swap discard support. It is called with >> swap_lock held, so it is meant to trigger action that finishes quickly. >> However, swap discard is an I/O request and can be used for taking longer >> actions. >> >> Links: >> [1] http://code.google.com/p/compcache/ >> > > Hmm, do you really need notify at *every* swap free ? > No batching is necessary ? >
We need notify for every swap free and no batching is desired, at least for compcache case.
Thanks, Nitin
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