linux-mips
[Top] [All Lists]

Re: tasklet latency and system calls on mips

To: "Sirotkin, Alexander" <demiurg@ti.com>
Subject: Re: tasklet latency and system calls on mips
From: Jun Sun <jsun@mvista.com>
Date: Thu, 14 Aug 2003 09:45:15 -0700
Cc: linux-mips@linux-mips.org, jsun@mvista.com
In-reply-to: <3F3B53C0.30408@ti.com>; from demiurg@ti.com on Thu, Aug 14, 2003 at 12:17:52PM +0300
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <3F3A411C.70603@ti.com> <20030813095446.C9655@mvista.com> <3F3B53C0.30408@ti.com>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.2.5i
On Thu, Aug 14, 2003 at 12:17:52PM +0300, Sirotkin, Alexander wrote:
> 
> I suspect that what happens is as follows :
> 
> system call arrives and while it's being processed and interrupt to one
> of the drivers arrives. This interrupt 
> schedules a tasklet which however is not executed after the system call
> finishes, 

The tasklet should be executed at the return of interrupt handling.
If not, there is a bug.


> only after the next timer
> interrupt which causes up to 10 ms latency (not all the time, only when
> somebody makes a system call).
> 

BTW, make sure tasklet_schedule() is indeed called in an interrupt handler.
I am not sure why will happen otherwise.

If you suspect it is a bug, you can easily trace them.  You may my
little tracing tool useful,

        
http://linux.junsun.net/patches/generic/experimental/030716.a-jstrace.patch

Jun

<Prev in Thread] Current Thread [Next in Thread>