can a bottom half be scheduled by another BH ??

[Vishwas Srivastava]

thanks a lot to all of you for the help.

Vishwas S


On Thu, Oct 3, 2013 at 8:48 PM, anish singh <anish198519851985 at gmail.com>wrote:

>
> On Oct 3, 2013 8:28 PM, "sujan dutta" <stoned.seven at gmail.com> wrote:
> >
> >
> > Yes you can, infact network subsystem softirq are reactive so it can run
> again.
> > however, reactivated softirq are not immediately process but until
> kernel handles the pending softirqs because it might introduce latency in
> user-space.
> > And for better performance, when pending BH grows excessively then
> family of kernel threads are wakes up to handle the load.
> Family of threads mentioned here is called ksoftirqd.
> Linux uses the ksoftirqd as the general solution to schedule softirq's to
> run before next interrupt and by putting them under scheduler control. Also
> this prevents consecutive softirq's from monopolizing the CPU. This also
> has the effect that the priority of ksoftirq needs to be considered when
> running very CPU-intensive applications and networking to get the proper
> balance of softirq/user balance. Increasing ksoftirq priority to 0
> (eventually more) is reported to cure problems with low network performance
> at high CPU load.
> I think softirq calling itself is a problem which is delicately managed by
> linux kernel developers and how to improve the code and logic is an active
> field where you can contribute.
>
> >
> >
> > On 27-Sep-2013, at 4:44 PM, Vishwas Srivastava (vishsriv) <
> vishsriv at cisco.com> wrote:
> >
> >> Hi Group,
> >>    I am a bit unclear if, I could schedule another BH while I am
> already running in a BH ?
> >> For example, if I am running in a SOFT IRQ, can I schedule a tasklet
> from there ??
> >>
> >> Thanks,
> >> Vishwas S
> >>
> >>
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