From: Peter Zijlstra <peterz@infradead.org>
To: Nikhil Rao <ncrao@google.com>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Turner <pjt@google.com>,
Mike Galbraith <efault@gmx.de>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 00/18] Increase resolution of load weights
Date: Thu, 21 Apr 2011 18:40:52 +0200 [thread overview]
Message-ID: <1303404052.2035.155.camel@laptop> (raw)
In-Reply-To: <1303332697-16426-1-git-send-email-ncrao@google.com>
On Wed, 2011-04-20 at 13:51 -0700, Nikhil Rao wrote:
>
> I would like to get some feedback on the direction of this patchset. Please let
> me know if there are alternative ways of doing this, and I'll be happy to
> explore them as well.
>
> The patchset applies cleanly to v2.6.39-rc4. It compiles for i386 and boots on
> x86_64. Beyond the basic checks, it has not been well tested yet.
>
> Major TODOs:
> - Detect overflow in update shares calculations (time * load), and set load_avg
> to maximum possible value (~0ULL).
> - tg->task_weight uses an atomic which needs to be updates to 64-bit on 32-bit
> machines. Might need to add a lock to protect this instead of atomic ops.
> - Check wake-affine math and effective load calculations for overflows.
> - Needs more testing and need to ensure fairness/balancing is not broken.
The code looks fairly ok and I can't fault the TODOs ;-)
I guess getting some measurements on the performance penalty on 32bit
would be nice -- if only to know about how bad it is.
And while its not perfect by a long stretch (we can still blow the whole
lot by creating a deep enough hierarchy) it should be much better.. the
only advantage of going with a full on wrapper solution would be that
plugging in an arbitrary precision type would be simple ;-)
next prev parent reply other threads:[~2011-04-21 16:38 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-20 20:51 [RFC][PATCH 00/18] Increase resolution of load weights Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 01/18] sched: introduce SCHED_POWER_SCALE to scale cpu_power calculations Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 02/18] sched: increase SCHED_LOAD_SCALE resolution Nikhil Rao
2011-04-28 9:54 ` Nikunj A. Dadhania
2011-04-28 17:11 ` Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 03/18] sched: use u64 for load_weight fields Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 04/18] sched: update cpu_load to be u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 05/18] sched: update this_cpu_load() to return u64 value Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 06/18] sched: update source_load(), target_load() and weighted_cpuload() to use u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 07/18] sched: update find_idlest_cpu() to use u64 for load Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 08/18] sched: update find_idlest_group() to use u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 09/18] sched: update division in cpu_avg_load_per_task to use div_u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 10/18] sched: update wake_affine path to use u64, s64 for weights Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 11/18] sched: update update_sg_lb_stats() to use u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 12/18] sched: Update update_sd_lb_stats() " Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 13/18] sched: update f_b_g() to use u64 for weights Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 14/18] sched: change type of imbalance to be u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 15/18] sched: update h_load to use u64 Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 16/18] sched: update move_task() and helper functions to use u64 for weights Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 17/18] sched: update f_b_q() to use u64 for weighted cpuload Nikhil Rao
2011-04-20 20:51 ` [RFC][Patch 18/18] sched: update shares distribution to use u64 Nikhil Rao
2011-04-21 6:16 ` [RFC][PATCH 00/18] Increase resolution of load weights Ingo Molnar
2011-04-21 16:32 ` Peter Zijlstra
2011-04-26 16:11 ` Nikhil Rao
2011-04-21 16:40 ` Peter Zijlstra [this message]
2011-04-28 7:07 ` Nikunj A. Dadhania
2011-04-28 11:48 ` Nikunj A. Dadhania
2011-04-28 12:12 ` Srivatsa Vaddagiri
2011-04-28 18:33 ` Nikhil Rao
2011-04-28 18:51 ` Paul Turner
2011-04-28 18:53 ` Paul Turner
2011-04-28 21:27 ` Nikhil Rao
2011-04-29 16:55 ` Paul Turner
2011-04-28 18:20 ` Nikhil Rao
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