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 20:34:19 +0200 Message-ID: <51F01E2B.5000201@acm.org> References: <51ED4E60.30203@acm.org> <51EFF018.7050409@mellanox.com> <51F0055F.7000703@acm.org> <51F0097C.4010806@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: <51F0097C.4010806-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 19:06, Or Gerlitz wrote: > On 24/07/2013 19:48, Bart Van Assche wrote: >> 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. > do you see it also on systems that don't run opensm? Yes. This happens both on systems running opensm and on systems not running opensm. A call trace from a system on which CPU load was higher than expected is as follows: # echo w >/proc/sysrq-trigger; dmesg -c SysRq : Show Blocked State task PC stack pid father kworker/u:7 D ffff88011fa125c0 0 181 2 0x00000000 ffff880114d63b48 0000000000000046 ffff8801158d1c40 ffff880114d63fd8 ffff880114d63fd8 ffff880114d63fd8 ffffffff81613440 ffff8801158d1c40 ffffffff817a7180 ffff880114d63b80 ffffffff817a7180 000000010000ebf9 Call Trace: [] schedule+0x29/0x70 [] schedule_timeout+0x10a/0x1e0 [] wait_for_common+0xd2/0x180 [] wait_for_completion_timeout+0x13/0x20 [] __mlx4_cmd+0x259/0x5e0 [mlx4_core] [] mlx4_SENSE_PORT+0x54/0xc0 [mlx4_core] [] mlx4_do_sense_ports+0xbf/0xd0 [mlx4_core] [] mlx4_sense_port+0x42/0xc0 [mlx4_core] [] process_one_work+0x16c/0x4b0 [] worker_thread+0x15d/0x450 [] kthread+0xc0/0xd0 [] ret_from_fork+0x7c/0xb0 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