[mmotm] Add swap slot free callback to block_device_operations
in [Kernel]
|
Prev: linux-2.6.31.9, linux-2.6.32.2, linux-2.6.33-rc2 -- Re: Device IDs for new Apple Wireless Keyboard
Next: [PATCH]btrfs: Remove a extra condition
From: Nitin Gupta on 6 Jan 2010 08:50 On 01/05/2010 04:28 PM, Hugh Dickins wrote: > On Tue, 5 Jan 2010, Nitin Gupta wrote: > >> This callback is required when RAM based devices are >> used as swap disks. One such device is ramzswap[1] which >> is used as compressed in-memory swap disk. For such >> devices, we need a callback as soon as a swap slot is no >> longer used to allow freeing memory allocated for this >> slot. Without this callback, stale data can quickly >> accumulate in memory defeating the whole purpose of >> such devices. >> >> Another user of this callback will be "preswap" as >> introduced by "Transcendent Memory" patches: >> http://lwn.net/Articles/367286/ >> (I intend to integrade preswap with ramzswap). >> >> [1] ramzswap: http://code.google.com/p/compcache/ >> >> Signed-off-by: Nitin Gupta <ngupta(a)vflare.org> > > Yes, thanks for your patience in putting this together: > I much prefer this version to all the other ways considered. > > (Though you should later add a comment, pointing out that this > callback is with swap_lock and often page table lock also held.) > I will send another patch for this. > We know that's unsatisfactory, but it is the nature of swap: > cutting some corners to get the job done without allocating > more memory. Having tried myself to do proper discard at > swap_free time, I know that is hard: and I believe you've > made the right decision to do it in this way for ramzswap. > > Acked-by: Hugh Dickins <hugh.dickins(a)tiscali.co.uk> > Thanks for the review. So, is this now going in mmotm tree? Nitin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |