From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH, RFC] mlx4: Avoid that mlx4_cmd_wait() contributes to the system load Date: Wed, 24 Jul 2013 18:48:31 +0200 Message-ID: <51F0055F.7000703@acm.org> References: <51ED4E60.30203@acm.org> <51EFF018.7050409@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51EFF018.7050409-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz Cc: linux-rdma , David Miller List-Id: linux-rdma@vger.kernel.org On 07/24/13 17:17, Or Gerlitz wrote: > On 22/07/2013 18:23, Bart Van Assche wrote: >> Avoid that kernel threads running mlx4_cmd_wait() contribute to the >> system load by setting the task state to TASK_INTERRUPTIBLE instead >> of TASK_UNINTERRUPTIBLE while waiting. This patch reduces the load >> average from about 0.5 to about 0.0 on an idle system with one mlx4 >> HCA and no IB cables connected. > > Before diving to the implications of the patch, lets discuss the > phenomena you see... > So the load average on this idle system is 0.5 or 0.05? > > I don't see 0.5 or a like on my systems that are installed with HCAs and > are idle. Could it > be that some IB management entity is repeatedly sending MADs to this > system? Hello Or, I saw a load of 0.5 with several different upstream kernels (3.6..3.10 at least). The only IB-related process that was running on the system was opensmd. This is definitely reproducible. It was only a month after I had noticed this phenomenon that I started searching for the root cause. Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html