can a bottom half be scheduled by another BH ??

[anish singh]

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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>
>
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