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: Tue, 25 Nov 2014 10:22:36 -0700 From: Khalid Aziz <khalid.aziz@...cle.com> To: Rik van Riel <riel@...hat.com>, tglx@...utronix.de, corbet@....net, mingo@...hat.com, hpa@...or.com, peterz@...radead.org, akpm@...ux-foundation.org, rientjes@...gle.com, ak@...ux.intel.com, mgorman@...e.de, raistlin@...ux.it, kirill.shutemov@...ux.intel.com, atomlin@...hat.com, avagin@...nvz.org, gorcunov@...nvz.org, serge.hallyn@...onical.com, athorlton@....com, oleg@...hat.com, vdavydov@...allels.com, daeseok.youn@...il.com, keescook@...omium.org, yangds.fnst@...fujitsu.com, sbauer@....utah.edu, vishnu.ps@...sung.com, axboe@...com, paulmck@...ux.vnet.ibm.com CC: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, linux-api@...r.kernel.org Subject: Re: [PATCH v3] sched/fair: Add advisory flag for borrowing a timeslice On 11/25/2014 08:25 AM, Rik van Riel wrote: > On 11/25/2014 09:52 AM, Khalid Aziz wrote: >> On 11/24/2014 07:03 PM, Rik van Riel wrote: >>> -----BEGIN PGP SIGNED MESSAGE----- >>> Hash: SHA1 >>> >>> On 11/24/2014 03:56 PM, Khalid Aziz wrote: >>>> sched/fair: Add advisory flag for borrowing a timeslice >>>> >>>> This patch adds a way for a task to request to borrow one >>>> timeslice from future if it is about to be preempted, so it could >>>> delay preemption and complete any critical task it is in the middle >>>> of. >>>> >>>> This feature helps with performance on databases and has been used >>>> for many years on other OSs by the databases. This feature helps in >>>> situation where a task acquires a lock before performing a critical >>>> operation on the database and happens to get preempted >>> >>> Why don't the other tasks that want the lock sleep on the >>> lock? >>> >>> I can see this "solution" help mostly with userspace spinlocks, >>> which are relics of a past era that need to die. There is no >>> way userspace spinlocks will not fail miserably on virtual >>> machines, and it is time to get rid of them. >> >> This solution indeed is for userspace spinlocks. Database code has been >> written with all critical locking implemented in userspace (as I have >> been told by database folks. I am not a database guy). > > They should fix that. Agreed, but that is a very large task for databases for sure and potentially for java as well (think exhaustive testing as well besides code re-write). I do not see this happening except as part of major re-architecture. In the mean time, if we can give them help without impacting kernel significantly for other users, it only makes Linux a more usable platform for them. Thanks, Khalid -- 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