Hello Chao, On Thu, Aug 21, 2014 at 05:09:19PM +0800, Chao Yu wrote: > Hi Minchan, > > > -----Original Message----- > > From: Minchan Kim [mailto:minchan@xxxxxxxxxx] > > Sent: Thursday, August 21, 2014 9:19 AM > > To: Chao Yu > > Cc: 'Sergey Senozhatsky'; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; ngupta@xxxxxxxxxx; > > 'Jerome Marchand'; 'Andrew Morton' > > Subject: Re: [PATCH] zram: add num_discards for discarded pages stat > > > > Hi Chao, > > > > On Wed, Aug 20, 2014 at 04:20:48PM +0800, Chao Yu wrote: > > > Hi Minchan, > > > > > > > -----Original Message----- > > > > From: Minchan Kim [mailto:minchan@xxxxxxxxxx] > > > > Sent: Wednesday, August 20, 2014 10:09 AM > > > > To: Sergey Senozhatsky > > > > Cc: Chao Yu; linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; ngupta@xxxxxxxxxx; 'Jerome > > > > Marchand'; 'Andrew Morton' > > > > Subject: Re: [PATCH] zram: add num_discards for discarded pages stat > > > > > > > > Hi Sergey, > > > > > > > > On Tue, Aug 19, 2014 at 08:25:00PM +0900, Sergey Senozhatsky wrote: > > > > > Hello, > > > > > > > > > > On (08/19/14 13:45), Chao Yu wrote: > > > > > > > On (08/15/14 11:27), Chao Yu wrote: > > > > > > > > Now we have supported handling discard request which is sended by filesystem, > > > > > > > > but no interface could be used to show information of discard. > > > > > > > > This patch adds num_discards to stat discarded pages, then export it to sysfs > > > > > > > > for displaying. > > > > > > > > > > > > > > > > > > > > > > a side question: we account discarded pages via slot free notify in > > > > > > > notify_free and via req_discard in num_discards. how about accounting > > > > > > > both of them in num_discards? because, after all, they account a number > > > > > > > of discarded pages (zram_free_page()). or there any particular reason we > > > > > > > want to distinguish. > > > > > > > > > > > > Yeah, I agree with you as I have no such reason unless there are our users' > > > > > > explicitly requirement for showing notify_free/num_discards separately later. > > > > > > > > > > > > How do you think of sending another patch to merge these two counts? > > > > > > > > > > > > > > > > Minchan, what do you think? let's account discarded pages in one place. > > > > > > > > First of all, I'd like to know why we need num_discards. > > > > It should be in description and depends on it whether we should merge both > > > > counts or separate. > > > > > > Oh, it's my mistaken. > > > > > > When commit 9b9913d80b2896ecd9e0a1a8f167ccad66fac79c (Staging: zram: Update > > > zram documentation) and commit e98419c23b1a189c932775f7833e94cb5230a16b (Staging: > > > zram: Document sysfs entries) description related to 'discard' stat was designed > > > and added to zram.txt and sysfs-block-zram, but without implementation of function > > > for handling discard request, description in documents were removed in commit > > > 8dd1d3247e6c00b50ef83934ea8b22a1590015de (zram: document failed_reads, > > > failed_writes stats) > > > > Thanks for letting me know the history. > > > > > > > > For now, we have already supported discard handling, so it's better to resume > > > the stat of discard number, this discard stat supports user one more kind of runtime > > > information of zram as other stats supported. > > > > > > How do you think? > > > > I'm not strong against the idea but just "resume is better" and > > "one more is problem as other stats supported" is not logical > > to me. > > OK, I assume maybe to match the principle for adopting and discarding > those stats in original version of zram will do some help, actually I'm wrong. > > > > > You should explain why we need such new stat so that user can take > > what kinds of benefit from that. Otherwise, we couldn't know the stat > > is best or not for the goal. > > Alright, it's reasonable from this perspective. > > > > > > > I might be paranoid about small stuff and I admit I'm not good for it, > > too but pz, understand that adding the new feature requires a > > good description which should include clear goal. > > Well, I can understand and accept that. > > > > > I hope I'm not discouraging. :) > > Nope, please let me try again, :) > > Since we have supported handling discard request in this commit > f4659d8e620d08bd1a84a8aec5d2f5294a242764 (zram: support REQ_DISCARD), zram got > one more chance to free unused memory whenever received discard request. But > without stating for discard request, there is no method for user to know whether > discard request has been handled by zram or how many blocks were discarded by > zram when user wants to know the effect of discard. > > In this patch, we add num_discards to stat discarded pages, and export it to > sysfs for users. Yeb, Thanks! >-- Kind regards, Minchan Kim -- 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>