linux-kernel - Re: [PATCH 6/6] perf: Increase round-robin fairness of flexible events

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:	Mon, 11 Jan 2010 09:04:40 +1100
From:	Paul Mackerras <paulus@...ba.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 6/6] perf: Increase round-robin fairness of flexible
 events

Frederic,

Nice to see someone working on the event scheduling in perf.

But I don't think this patch makes sense:

> Group of flexible events are round-robined in each tick so that
> each group has its chance to be scheduled. But the fairness
> per group granularity doesn't propagate inside the groups
> themselves.
> 
> If only the first events of each groups have a chance to make
> their way, the remaining ones will never be scheduled.
> 
> Hence this patch propagates the round-robin to the events
> inside the groups.

The semantic of a group is that either all of the events in the group
are scheduled in, or none of them are.  So it doesn't make sense to
talk about fairness within a group, and I don't see any point to
rotating the elements of the sibling_list.  Or have I misunderstood
what you're aiming at?

Paul.
--
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/