On 2018/2/11 9:55, heyunlei wrote: > > >> -----Original Message----- >> From: Chao Yu [mailto:c...@kernel.org] >> Sent: Friday, February 09, 2018 9:37 PM >> To: heyunlei; jaeg...@kernel.org; Yuchao (T); >> linux-f2fs-devel@lists.sourceforge.net >> Subject: Re: [f2fs-dev] [PATCH] f2fs: remove unneed reada during build free >> nids >> >> On 2018/2/9 11:58, Yunlei He wrote: >>> This patch remove unneed reada during build free nids. >>> If few nids left, three will introduce a lot of no hit >>> read io. >> >> I guess it is due to be lack of commit c1fe3e981440 ("Revert "f2fs: >> reuse nids more aggressively""), before that commit, we will update >> .next_scan_nid randomly instead of updating it ascendingly, then >> during __build_free_nids we may readahead NAT pages starting from >> random position. > > I think commit c1fe3e981440 will reduce fragment of nat area, it > will locate all used nids at the left head of nat area, which I think > will do benefit to WA ?
Yup, IMO, it can reduce WA. ;) Also, there is another patch intends to reduce WA by adjusting allocation policy of free nid. FYI https://patchwork.kernel.org/patch/10084653/ > > e.g, if we have used 10000 nids, which will hold 10000/455 blocks at least. > Without this commit, the blocks taken for nids will expansion, may be 10000 > blocks in the worst case, at this time, if we update node info, we will > produce > more nat IOs? That's right. Thanks, > >> >> Could try that commit to check IO again? >> >> Thanks, ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
