2012-04-08 오후 10:50, Alex Lemberg 쓴 글: > Hi Arnd, > > Regarding time to issue discard/TRIM commands: > It would be advised to issue the discard command immediately after > deleting/freeing a SWAP cluster (i.e. as soon as it becomes available).
Is it still good with page size, not cluster size? > > Regarding SWAP page size: > Working with as large as SWAP pages as possible would be recommended > (preferably 64KB). Also, writing in a sequential manner as much as possible > while swapping large quantities of data is also advisable. > > SWAP pages and corresponding transactions should be aligned to the SWAP page > size (i.e. 64KB above), the alignment should correspond to the physical > storage "LBA 0", i.e. to the first LBA of the storage device (and not to a > logical/physical partition). > I have a curiosity on above comment is valid on Samsung and other eMMC. Hyojin, Could you answer? > Thanks, > Alex > >> -----Original Message----- >> From: Arnd Bergmann [mailto:[email protected]] >> Sent: Monday, April 02, 2012 5:55 PM >> To: Hugh Dickins >> Cc: [email protected]; Rik van Riel; linux- >> [email protected]; Alex Lemberg; [email protected]; Luca >> Porzio (lporzio); [email protected]; Hyojin Jeong; kernel- >> [email protected]; Yejin Moon >> Subject: Re: swap on eMMC and other flash >> >> On Monday 02 April 2012, Hugh Dickins wrote: >>> On Mon, 2 Apr 2012, Arnd Bergmann wrote: >>>> >>>> Another option would be batched discard as we do it for file >> systems: >>>> occasionally stop writing to swap space and scanning for areas that >>>> have become available since the last discard, then send discard >>>> commands for those. >>> >>> I'm not sure whether you've missed "swapon --discard", which switches >>> on discard_swap_cluster() just before we allocate from a new cluster; >>> or whether you're musing that it's no use to you because you want to >>> repurpose the swap cluster to match erase block: I'm mentioning it in >>> case you missed that it's already there (but few use it, since even >>> done at that scale it's often more trouble than it's worth). >> >> I actually argued that discard_swap_cluster is exactly the right thing >> to do, especially when clusters match erase blocks on the less capable >> devices like SD cards. >> >> Luca was arguing that on some hardware there is no point in ever >> submitting a discard just before we start reusing space, because >> at that point it the hardware already discards the old data by >> overwriting the logical addresses with new blocks, while >> issuing a discard on all blocks as soon as they become available >> would make a bigger difference. I would be interested in hearing >> from Hyojin Jeong and Alex Lemberg what they think is the best >> time to issue a discard, because they would know about other hardware >> than Luca. >> >> Arnd > > PLEASE NOTE: The information contained in this electronic mail message is > intended only for the use of the designated recipient(s) named above. If the > reader of this message is not the intended recipient, you are hereby notified > that you have received this message in error and that any review, > dissemination, distribution, or copying of this message is strictly > prohibited. If you have received this communication in error, please notify > the sender by telephone or e-mail (as shown above) immediately and destroy > any and all copies of this message in your possession (whether hard copies or > electronically stored copies). > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to [email protected]. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: <a href=ilto:"[email protected]"> [email protected] </a> > -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
