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, 2 Dec 2020 06:38:12 -0800 From: Andy Lutomirski <luto@...capital.net> To: Peter Zijlstra <peterz@...radead.org> Cc: Nicholas Piggin <npiggin@...il.com>, linux-kernel@...r.kernel.org, x86@...nel.org, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org, Anton Blanchard <anton@...abs.org> Subject: Re: [PATCH 6/8] lazy tlb: shoot lazies, a non-refcounting lazy tlb option > On Dec 2, 2020, at 6:20 AM, Peter Zijlstra <peterz@...radead.org> wrote: > > On Sun, Nov 29, 2020 at 02:01:39AM +1000, Nicholas Piggin wrote: >> + * - A delayed freeing and RCU-like quiescing sequence based on >> + * mm switching to avoid IPIs completely. > > That one's interesting too. so basically you want to count switch_mm() > invocations on each CPU. Then, periodically snapshot the counter on each > CPU, and when they've all changed, increment a global counter. > > Then, you snapshot the global counter and wait for it to increment > (twice I think, the first increment might already be in progress). > > The only question here is what should drive this machinery.. the tick > probably. > > This shouldn't be too hard to do I think. > > Something a little like so perhaps? I don’t think this will work. A CPU can go idle with lazy mm and nohz forever. This could lead to unbounded memory use on a lightly loaded system.
Powered by blists - more mailing lists