From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ashoka K Subject: Re: Need help to measure and tune the latency in Linux RT Date: Tue, 30 Apr 2013 18:47:05 +0530 Message-ID: References: <20130430111021.GC31290@titan.lakedaemon.net> <517FB553.3000001@meduna.org> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=2QoEQyoqdex/nLlyflQOjB90rsKjqgsC6rjqxXLFDQg=; b=UTjnlV5UF1pArYxqQAUFEUNxgSHnvJOkWH+MPKg9A+5LfBEP+IVKxaCAAQJbdoSHGT TZRlYmadSIfFqrfL+AobpQGJjlz2rAMF8Zj4BfD9jIHFBrGhpUwP3cD5p/D3Bt0neSfU pYgjzEg3n/kVpaBPiv8FX/gUcl9+tR0nv0Skqiwk3x0VADM36Y7AMPvAx9tyxkyepVlz EGhfRgknTJPh1bIlySvcD1rmWJXGasGzVULTs1aLqew5Y05Ke8LDaEAALwgYUwfrHXAd ilQFiCWhVNkeaFSZzBreEpMNVV76iK+DuK4t1hSJuwhP4R2/PcxZRqqzxHgCcK9zRUCt nIEA== In-Reply-To: <517FB553.3000001@meduna.org> Sender: linux-newbie-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Stanislav Meduna Cc: linux-embedded@vger.kernel.org, linux-newbie@vger.kernel.org, Linux ARM Kernel , linux-rt-users@vger.kernel.org Thanks for all the replies. I am stuck with this issue for more tan a month. Explained this in more detail at: http://stackoverflow.com/questions/15805231/need-to-improve-the-linux-performance-for-embedded-system But with no response from anyone. I use PREEMPT patch for 2.6.33 vanilla kernel. I have pasted all the processes running on my system: PID USER VSZ STAT COMMAND 1 root 3192 S init 2 root 0 SW [kthreadd] 3 root 0 SW [ksoftirqd/0] 4 root 0 SW [events/0] 5 root 0 SW [khelper] 8 root 0 SW [async/mgr] 84 root 0 SW [sync_supers] 86 root 0 SW [bdi-default] 88 root 0 SW [kblockd/0] 91 root 0 SW [omap2_mcspi] 116 root 0 SW [rpciod/0] 123 root 0 SW [kswapd0] 124 root 0 SW [aio/0] 125 root 0 SW [nfsiod] 126 root 0 SW< [kslowd001] 127 root 0 SW< [kslowd000] 128 root 0 SW [crypto/0] 267 root 0 SW [mtdblockd] 351 root 0 SWN [jffs2_gcd_mtd8] 359 root 3192 S /sbin/syslogd 361 root 3192 S /usr/sbin/telnetd 364 root 1996 S vsftpd 410 root 43844 S my_appl 416 root 56412 S < my_appl 417 root 84804 S my_appl 418 root 43844 S my_appl 419 root 84824 S my_appl 430 root 46552 S < my_appl The process my_appl is my application processes. the ksoftirq is running with SCHED_OTHER. $ chrt -p 3 pid 3's current scheduling policy: SCHED_OTHER pid 3's current scheduling priority: 0 I will test by changing ksoftirq priority to see how it works. Regards Ashoka. K On Tue, Apr 30, 2013 at 5:43 PM, Stanislav Meduna wrote: >>> This critical thread is at RR priority 50. > > Try to put it higher than the irq thread handling your HD hardware. > I've even encountered hardware where I had to put the ATA thread > in the SHED_OTHER domain - see [1] for the thread. > >>> I used a HR timer thread with RR pri 55 to wakeup the critical thread >>> every 1 milli sec to do the job. > > Which prio is the ksoftirqd running at? The HRTIMER interrupts are > routed through it so it also has to be high enough. > > I got burned with this myself [2] > > Regards > Stano > > [1] http://www.spinics.net/lists/linux-rt-users/msg08711.html > [2] http://www.spinics.net/lists/linux-rt-users/msg08745.html > -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" 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.linux-learn.org/faqs