[lkml]   [2005]   [Mar]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: help needed pls. scheduler(kernel 2.6) + hyperthreaded related questions?
few more trivial Q's (bear with me  I'm a newbie to kernel world):

1) As I said I have a process that spawns 2 threads(thread A and B).I am
trying to measure the exact time @ which they are being scheduled.For this I
am using the rdtsc() (when threads A and B come) in enqueue_task()..where
they are being inserted into the priority array.
Is this a correct way of measuring?

2) also in "tgid" the id of my process and each of
threads hav a unique pid??

3) I saw frm the kernel docs tht realtime tasks hav priority 0 to 99. So
using setscheduler means do I have to enforce a priority in one of these
ranges to make my threads as soft/hard realtime task.

thanks in advance for your patience.

>From: Nick Piggin <>
>To: Arun Srinivas <>
>Subject: Re: help needed pls. scheduler(kernel 2.6) + hyperthreaded related
>Date: Wed, 23 Mar 2005 18:37:16 +1100
>Arun Srinivas wrote:
>>If the SMT (apart from SMP) support is enabled in the .config file, does
>>the kernel recogonize the 2 logical processor as 2 logical or 2 physical
>You shouldn't be able to select SMT if SMP is not enabled.
>If SMT and SMP is selected, then the scheduler will recognise
>the 2 processors as logical ones.
>>Also, as the hyperthreaded processor may schedule 2 threads in the 2
>>logical cpu's, and it may not necessarily be form the same process i.e.,
>>the 2 thread it schedules may be from the same or from the different
>>So, is there any way I can tell the scheduler (assuming I make the
>>scheduler recogonize my 2 threads..i.e., it knows their pid) to schedule
>>always my 2 threads @ the same time? How do I go abt it?
>Use sched_setaffinity to force each thread onto the particular
>CPU. Use sched_setscheduler to acquire a realtime scheduling
>policy. Then use mutexes to synchronise your threads so they
>run the desired code segment at the same time.

Screensavers unlimited! Download

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-04-06 13:30    [W:0.064 / U:9.680 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site