linux-kernel - Re: [bisected] pre-3.16 regression on open() scalability

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 17 Jun 2014 17:15:17 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Dave Hansen <dave.hansen@...el.com>
Cc:	paulmck@...ux.vnet.ibm.com, LKML <linux-kernel@...r.kernel.org>,
	Josh Triplett <josh@...htriplett.org>,
	"Chen, Tim C" <tim.c.chen@...el.com>,
	Christoph Lameter <cl@...ux.com>
Subject: Re: [bisected] pre-3.16 regression on open() scalability

> It also ends up eating a new cacheline in a bunch of pretty hot paths.
> It would be nice to be able to keep the fast path part of this as at
> least read-only.
> 
> Could we do something (functionally) like the attached patch?  Instead
> of counting cond_resched() calls, we could just specify some future time
> by which we want have a quiescent state.  We could even push the time to
> be something _just_ before we would have declared a stall.

I still think it's totally the wrong place. cond_resched() is in so
many fast paths (every lock, every allocation). It just doesn't
make sense to add non essential things like this to it.

I would be rather to just revert the original patch.

-Andi
--
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/