Messages in this thread | | | Date | Wed, 12 Aug 2009 18:59:42 +0530 | From | Nitin Gupta <> | Subject | Re: [RFC][PATCH] swap: send callback when swap slot is freed |
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On 08/12/2009 06:26 PM, Ingo Molnar wrote: > * Nitin Gupta<ngupta@vflare.org> wrote: > >> (Re-sending since I didn't get any reply last time) >> >> 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.
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> > Shouldnt this be all be unconditional? Sounds like a reasonable VM > callback. The patch would become a lot smaller as well. >
I also think this can be made unconditional as it makes the patch much cleaner. I made it conditional just to be on path of least resistance :)
Thanks for looking into this. I will resend the patch removing all the #ifdef'ery.
Nitin
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