lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 19 Jan 2011 11:17:45 +0900 From: Minchan Kim <minchan.kim@...il.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Miklos Szeredi <miklos@...redi.hu>, kamezawa.hiroyu@...fujitsu.com, nishimura@....nes.nec.co.jp, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v4] mm: add replace_page_cache_page() function On Wed, Jan 19, 2011 at 10:48 AM, Andrew Morton <akpm@...ux-foundation.org> wrote: > On Wed, 19 Jan 2011 10:24:09 +0900 Minchan Kim <minchan.kim@...il.com> wrote: > >> > >> > This is all pretty ugly and inefficient. >> > >> > We call __remove_from_page_cache() which does a radix-tree lookup and >> > then fiddles a bunch of accounting things. >> > >> > Then we immediately do the same radix-tree lookup and then undo the >> > accounting changes which we just did. __And we do it in an open-coded >> > fashion, thus giving the kernel yet another code site where various >> > operations need to be kept in sync. >> > >> > Would it not be better to do a single radix_tree_lookup_slot(), >> > overwrite the pointer therein and just leave all the ancilliary >> > accounting unaltered? >> >> I agree single radix_tree_lookup but accounting still is needed since >> newpage could be on another zone. What we can remove is just only >> mapping->nrpages. > > Well. We only need to do inc/dec_zone_state if the zones are > different. Perhaps the zones-equal case is worth optimising for, > dunno. > > Also, the radix_tree_preload() should be unneeded. Agree. In summary, optimization points are following as. 1) remove radix_tree_preload 2) single radix_tree_lookup_slot and replace radix tree slot 3) page accounting optimization if both pages are in same zone. I hope we mm guys optimize the above things with TODO. (Except freepage issue I mentioned.) So I want Miklos resend the patch with solving freepage issue and NOTE of TODO in description or comment. -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists