Hello Dan, On Thu, Nov 21, 2013 at 8:42 AM, Bob Liu <bob.liu@xxxxxxxxxx> wrote: > Hi Dan, > > On 11/21/2013 03:49 AM, Dan Streetman wrote: >> Currently, zswap is writeback cache; stored pages are not sent >> to swap disk, and when zswap wants to evict old pages it must >> first write them back to swap cache/disk manually. This avoids >> swap out disk I/O up front, but only moves that disk I/O to >> the writeback case (for pages that are evicted), and adds the >> overhead of having to uncompress the evicted pages, and adds the >> need for an additional free page (to store the uncompressed page) >> at a time of likely high memory pressure. Additionally, being >> writeback adds complexity to zswap by having to perform the >> writeback on page eviction. >> > > Good work! > >> This changes zswap to writethrough cache by enabling >> frontswap_writethrough() before registering, so that any >> successful page store will also be written to swap disk. All the >> writeback code is removed since it is no longer needed, and the >> only operation during a page eviction is now to remove the entry >> from the tree and free it. >> Thanks for your work. I reviewed this patch, and it is good to me. However, I am skeptical about it because: 1. it will add more IO than original zswap, how does it result in a performance improvement ? 2. most embedded device use NAND, more IO will reduce its working life Regards > Could you do some testing using eg. SPECjbb? And compare the result with > original zswap. > > Thanks, > -Bob > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>