Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932351Ab1FGSe1 (ORCPT ); Tue, 7 Jun 2011 14:34:27 -0400 Received: from ccserver2.unican.es ([130.206.5.101]:57016 "EHLO ccserver2.unican.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932311Ab1FGSeZ (ORCPT ); Tue, 7 Jun 2011 14:34:25 -0400 Message-ID: <4DEE6F4E.1030107@unican.es> Date: Tue, 7 Jun 2011 20:34:54 +0200 From: Monica Puig-Pey User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.17) Gecko/20110424 Thunderbird/3.1.10 MIME-Version: 1.0 To: CC: , Rolando Martins , , Subject: Re: Changing Kernel thread priorities 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> <4DEDF366.6000706@cfl.rr.com> In-Reply-To: <4DEDF366.6000706@cfl.rr.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [193.144.198.131] X-imss-version: 2.054 X-imss-result: Passed X-imss-scanInfo: M:P L:E SM:0 X-imss-tmaseResult: TT:0 TS:0.0000 TC:00 TRN:0 TV:6.5.1024(18186.001) X-imss-scores: Clean:94.47410 C:2 M:3 S:5 R:5 X-imss-settings: Baseline:1 C:1 M:2 S:2 R:2 (0.0000 0.0000) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5382 Lines: 181 El 07/06/11 11:46, Mark Hounschell escribi?: > 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?: >>>> On 06/06/2011 07:58 AM, Monica Puig-Pey wrote: >>>>> El 06/06/11 13:54, Rolando Martins escribi?: >>>>>> Hi, >>>>>> I use the following: >>>>>> >>>>>> PIDs=$(ps -eLo pid,cls,rtprio,pri,nice,cmd | grep -i "irq" | awk '{ >>>>>> print $1; }' | xargs echo) >>>>>> for i in $PIDs >>>>>> do >>>>>> ret=$(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 with >>>>>>> it. >>>>>>> I want to change the priority of this thread, so that I can >>>>>>> specify 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?nica >>>>>>> >>>>>>> -- >>>>>>> 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 >>>>>>> >>>>> >>>>> I need to change the priority from inside the driver, when creating >>>>> 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 create an >>>> IOCTL for your driver that user land can call that either returns the >>>> 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 IOCTL >>> (kernel context) for changing its priority? >>> >> >> The PID can be obtained from within the interrupt handler its self via >> 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 priority >> 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 = {.sched_priority = MAX_RT_PRIO }; > > TSK = current; > > Code snippet from BH: > > if (((rtom_rtprio != 0) && > (rtom_rtprio != PARAM.sched_priority)) || > (my_rtom_rtprio[BOARD] != rtom_rtprio)) { > > PARAM.sched_priority = rtom_rtprio; > my_rtom_rtprio[COUNT] = rtom_rtprio; > sched_setscheduler(TSK, SCHED_FIFO, &PARAM); > > set_cpus_allowed(TSK, rtom_devices[BOARD].irq_cpu_mask); > rtom_devices[BOARD].irq_task_pid = TSK->pid; > } > > rtom_rtprio and irq_cpu_mask are set by userland via an IOCTL. An > interrupt must occur for this to happen and my BOARD never shares IRQs. > > Mark > Thanks, your idea seems to be very useful to me. I was doing it very similar, but I didn't use the "current" variable to know the task_struct *. I have tried your suggestion on an easy example, but it didn't work. Insmod returns through the kernel [11334.895499] kthread: Unknown symbol sched_setscheduler Code shown below: #include #include #include #include #include #include #include struct task_struct *ts; int thread(void *data) { struct task_struct *TSK; struct sched_param PARAM = {.sched_priority = MAX_RT_PRIO }; TSK = current; PARAM.sched_priority = 50; sched_setscheduler(TSK, SCHED_FIFO, &PARAM); // <-- unknown symbol?? while(1){ printk("Hi I am kernel thread!\n"); msleep(100); if (kthread_should_stop()) break; } return 0; } int init_module(void) { printk(KERN_INFO "init_module() called\n"); ts=kthread_run(thread,NULL,"kthread"); return 0; } void cleanup_module(void) { printk(KERN_INFO "cleanup_module() called\n"); kthread_stop(ts); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/