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From: Jun Sun <jsun@mvista.com>
To: "Sirotkin, Alexander" <demiurg@ti.com>
Cc: linux-mips@linux-mips.org, jsun@mvista.com
Subject: Re: tasklet latency and system calls on mips
Date: Thu, 14 Aug 2003 09:45:15 -0700	[thread overview]
Message-ID: <20030814094515.B1203@mvista.com> (raw)
In-Reply-To: <3F3B53C0.30408@ti.com>; from demiurg@ti.com on Thu, Aug 14, 2003 at 12:17:52PM +0300

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

  reply	other threads:[~2003-08-14 16:45 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-08-13 13:46 tasklet latency and system calls on mips Sirotkin, Alexander
2003-08-13 16:54 ` Jun Sun
2003-08-14  9:17   ` Sirotkin, Alexander
2003-08-14 16:45     ` Jun Sun [this message]
2003-08-18 15:29       ` Sirotkin, Alexander
2003-08-18 17:08         ` Jun Sun

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