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: Thu, 25 Jun 2015 21:44:28 -0400 From: Rik van Riel <riel@...hat.com> To: Vlastimil Babka <vbabka@...e.cz>, "Kirill A. Shutemov" <kirill@...temov.name>, Ebru Akagunduz <ebru.akagunduz@...il.com> CC: linux-mm@...ck.org, akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com, n-horiguchi@...jp.nec.com, aarcange@...hat.com, iamjoonsoo.kim@....com, xiexiuqi@...wei.com, gorcunov@...nvz.org, linux-kernel@...r.kernel.org, mgorman@...e.de, rientjes@...gle.com, aneesh.kumar@...ux.vnet.ibm.com, hughd@...gle.com, hannes@...xchg.org, mhocko@...e.cz, boaz@...xistor.com, raindel@...lanox.com Subject: Re: [RFC v2 3/3] mm: make swapin readahead to improve thp collapse rate On 06/24/2015 08:33 AM, Vlastimil Babka wrote: > On 06/22/2015 03:37 AM, Rik van Riel wrote: >> On 06/21/2015 02:11 PM, Kirill A. Shutemov wrote: >>> On Sat, Jun 20, 2015 at 02:28:06PM +0300, Ebru Akagunduz wrote: >>>> + __collapse_huge_page_swapin(mm, vma, address, pmd, pte); >>>> + >>> >>> And now the pages we swapped in are not isolated, right? >>> What prevents them from being swapped out again or whatever? >> >> Nothing, but __collapse_huge_page_isolate is run with the >> appropriate locks to ensure that once we actually collapse >> the THP, things are present. >> >> The way do_swap_page is called, khugepaged does not even >> wait for pages to be brought in from swap. It just maps >> in pages that are in the swap cache, and which can be >> immediately locked (without waiting). >> >> It will also start IO on pages that are not in memory >> yet, and will hopefully get those next round. > > Hm so what if the process is slightly larger than available memory and really > doesn't touch the swapped out pages that much? Won't that just be thrashing and > next round you find them swapped out again? Yes, it might. However, all the policy smarts are in patch 2/3, not in patch 3/3 (which has the mechanism). I suspect the code could use some more smarts, but I am not quite sure what they should be... -- All rights reversed -- 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