From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Hounschell Subject: Re: Changing Kernel thread priorities Date: Tue, 07 Jun 2011 05:46:14 -0400 Message-ID: <4DEDF366.6000706@cfl.rr.com> References: <4DEA1BA9.7020303@unican.es><4DEA1F22.6000603@unican.es><4DEA255 B.2050503@unican.es><4DECBE44.2070803@unican.es> <4DECC0DF.8070209@unican.es> <4DED051A.6020702@compro.net> <4DEDE411.6010807@unican.es> <4DEDEBFF.10907@cfl.rr.com> Reply-To: dmarkh@cfl.rr.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: dmarkh@cfl.rr.com, markh@compro.net, Rolando Martins , linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org To: Monica Puig-Pey Return-path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120]:58022 "EHLO cdptpa-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750849Ab1FGJqQ convert rfc822-to-8bit (ORCPT ); Tue, 7 Jun 2011 05:46:16 -0400 In-Reply-To: <4DEDEBFF.10907@cfl.rr.com> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 06/07/2011 05:14 AM, Mark Hounschell wrote: > On 06/07/2011 04:40 AM, Monica Puig-Pey wrote: >> El 06/06/11 18:49, Mark Hounschell escribi=F3: >>> On 06/06/2011 07:58 AM, Monica Puig-Pey wrote: >>>> El 06/06/11 13:54, Rolando Martins escribi=F3: >>>>> Hi, >>>>> I use the following: >>>>> >>>>> PIDs=3D$(ps -eLo pid,cls,rtprio,pri,nice,cmd | grep -i "irq" | aw= k '{ >>>>> print $1; }' | xargs echo) >>>>> for i in $PIDs >>>>> do >>>>> ret=3D$(chrt -f -p 99 $i) >>>>> done >>>>> >>>>> This will change the kernel thread associated with an irq handler= to >>>>> RT FIFO prio 99. >>>>> Just change the script to your specific interrupt. >>>>> >>>>> Hope it helps, >>>>> Rolando >>>>> >>>>> On Mon, Jun 6, 2011 at 12:47 PM, Monica Puig-Pey >>>>> wrote: >>>>>> I am writing a driver which has one kernel thread associated wit= h it. >>>>>> I want to change the priority of this thread, so that I can spec= ify the >>>>>> order in which it is scheduled following an interrupt. >>>>>> I'm using: >>>>>> >>>>>> sched_setscheduler(struct task_struct *, int, struct sched_param= *); >>>>>> >>>>>> but it doesn't work. I tried to change the priority from the >>>>>> init_module, >>>>>> and also from the Kernel Thread, but there is no way. >>>>>> >>>>>> Kernel version is 2.6.31-11-rt >>>>>> >>>>>> What do I call to change a kernel thread priority? >>>>>> >>>>>> Thanks you very much >>>>>> >>>>>> M=F3nica >>>>>> >>>>>> -- >>>>>> To unsubscribe from this list: send the line "unsubscribe >>>>>> linux-rt-users" in >>>>>> the body of a message to majordomo@vger.kernel.org >>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.htm= l >>>>>> >>>> >>>> I need to change the priority from inside the driver, when creatin= g the >>>> kernel thread. >>>> Your script is useful but it is done in user context, >>>> Any other help please? >>> >>> What I do is record the PID of the thread in the driver, then creat= e an >>> IOCTL for your driver that user land can call that either returns t= he >>> PID so you can do it in user land, or cause the IOCTL code to do it= in >>> the driver. >>> >>> The same can be done with the affinity of the IRQ if you record the= IRQ >>> number. >>> >>> Mark >>> -- >>> To unsubscribe from this list: send the line "unsubscribe >>> linux-rt-users" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> But I don't have de PID of my Kthread, I only have the task_struc * = that >> gives me the function: >> >> struct task_struct *kthread_create(int (*threadfn)(void *data), >> void *data, >> const char namefmt[], ...) >> >> How could I get the PID, and which function should I use in the IOCT= L >> (kernel context) for changing its priority? >> > > The PID can be obtained from within the interrupt handler its self vi= a > current->pid. > Obviously an interrupt has to occur first but after one interrupt you= have it. > > Actually I had forgot how I handled this. Where I change the RT prior= ity > and cpu affinity is in what used to be called the Bottom Half and the= IOCTL > referred to above simply tells the BH to do it and with what values. > In interrupt handler code snippet: struct task_struct *TSK; struct sched_param PARAM =3D {.sched_priority =3D MAX_RT_PRIO }; TSK =3D current; Code snippet from BH: if (((rtom_rtprio !=3D 0) && (rtom_rtprio !=3D PARAM.sched_priority)) || (my_rtom_rtprio[BOARD] !=3D rtom_rtprio)) { PARAM.sched_priority =3D rtom_rtprio; my_rtom_rtprio[COUNT] =3D rtom_rtprio; sched_setscheduler(TSK, SCHED_FIFO, &PARAM); set_cpus_allowed(TSK, rtom_devices[BOARD].irq_cpu_mask= ); rtom_devices[BOARD].irq_task_pid =3D TSK->pid; } rtom_rtprio and irq_cpu_mask are set by userland via an IOCTL. An inter= rupt=20 must occur for this to happen and my BOARD never shares IRQs. Mark -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html