On Thu, Mar 14, 2013 at 09:10:48AM -0700, Dan Magenheimer wrote: >> From: Wanpeng Li [mailto:liwanp@xxxxxxxxxxxxxxxxxx] >> Sent: Wednesday, March 13, 2013 6:21 PM >> To: Dan Magenheimer >> Cc: Andrew Morton; Greg Kroah-Hartman; Dan Magenheimer; Seth Jennings; Konrad Rzeszutek Wilk; Minchan >> Kim; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH 4/4] zcache: add pageframes count once compress zero-filled pages twice >> >> On Wed, Mar 13, 2013 at 09:42:16AM -0700, Dan Magenheimer wrote: >> >> From: Wanpeng Li [mailto:liwanp@xxxxxxxxxxxxxxxxxx] >> >> Sent: Wednesday, March 13, 2013 1:05 AM >> >> To: Andrew Morton >> >> Cc: Greg Kroah-Hartman; Dan Magenheimer; Seth Jennings; Konrad Rzeszutek Wilk; Minchan Kim; linux- >> >> mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Wanpeng Li >> >> Subject: [PATCH 4/4] zcache: add pageframes count once compress zero-filled pages twice >> > >> >Hi Wanpeng -- >> > >> >Thanks for taking on this task from the drivers/staging/zcache TODO list! >> > >> >> Since zbudpage consist of two zpages, two zero-filled pages compression >> >> contribute to one [eph|pers]pageframe count accumulated. >> > >> >> Hi Dan, >> >> >I'm not sure why this is necessary. The [eph|pers]pageframe count >> >is supposed to be counting actual pageframes used by zcache. Since >> >your patch eliminates the need to store zero pages, no pageframes >> >are needed at all to store zero pages, so it's not necessary >> >to increment zcache_[eph|pers]_pageframes when storing zero >> >pages. >> > >> >> Great point! It seems that we also don't need to caculate >> zcache_[eph|pers]_zpages for zero-filled pages. I will fix >> it in next version. :-) > >Hi Wanpeng -- > Hi Dan, >I think we DO need to increment/decrement zcache_[eph|pers]_zpages >for zero-filled pages. > >The main point of the counters for zpages and pageframes >is to be able to calculate density == zpages/pageframes. >A zero-filled page becomes a zpage that "compresses" to zero bytes >and, as a result, requires zero pageframes for storage. >So the zpages counter should be increased but the pageframes >counter should not. It is reasonable to me, I will increment/decrement zcache_[eph|pers]_zpages in next version. > >If you are changing the patch anyway, I do like better the use >of "zero_filled_page" rather than just "zero" or "zero page". >So it might be good to change: > >handle_zero_page -> handle_zero_filled_page >pages_zero -> zero_filled_pages >zcache_pages_zero -> zcache_zero_filled_pages > >and maybe > >page_zero_filled -> page_is_zero_filled Great rename! :-) Regards, Wanpeng Li > >Thanks, >Dan > >-- >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> -- 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>