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: Fri, 26 Aug 2016 21:22:26 -0700 From: Josh Triplett <josh@...htriplett.org> To: Ben Maurer <bmaurer@...com> Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Linus Torvalds <torvalds@...ux-foundation.org>, Dave Watson <davejwatson@...com>, Peter Zijlstra <peterz@...radead.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Boqun Feng <boqun.feng@...il.com>, Andy Lutomirski <luto@...capital.net>, linux-kernel <linux-kernel@...r.kernel.org>, linux-api <linux-api@...r.kernel.org>, Paul Turner <pjt@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, Russell King <linux@....linux.org.uk>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <hpa@...or.com>, Andrew Hunter <ahh@...gle.com>, Andi Kleen <andi@...stfloor.org>, Chris Lameter <cl@...ux.com>, rostedt <rostedt@...dmis.org>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Michael Kerrisk <mtk.manpages@...il.com> Subject: Re: [RFC PATCH v8 1/9] Restartable sequences system call On Thu, Aug 25, 2016 at 05:56:25PM +0000, Ben Maurer wrote: > rseq opens up a whole world of algorithms to userspace – algorithms > that are O(num CPUs) and where one can have an extremely fast fastpath > at the cost of a slower slow path. Many of these algorithms are in use > in the kernel today – per-cpu allocators, RCU, light-weight reader > writer locks, etc. Even in cases where these APIs can be implemented > today, a rseq implementation is often superior in terms of > predictability and usability (eg per-thread counters consume more > memory and are more expensive to read than per-cpu counters). > > Isn’t the large number of uses of rseq-like algorithms in the kernel a > pretty substantial sign that there would be demand for similar > algorithms by user-space systems programmers? Yes and no. It provides a substantial sign that such algorithms could and should exist; however "someone should do this" doesn't demonstrate that someone *will*. I do think we need a concrete example of a userspace user with benchmark numbers that demonstrate the value of this approach. Mathieu, do you have a version of URCU that can use rseq to work per-CPU rather than per-thread? URCU's data structures would work as a benchmark. Ben, Mathieu, Dave, do you have jemalloc benchmark numbers with and without rseq? (As well as memory usage numbers for the reduced memory usage of per-CPU pools rather than per-thread pools?)
Powered by blists - more mailing lists