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Re: pthread_create() slow for many threads; also time to revisit 64b context switch optimization?

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From: Ulrich Drepper <drepper@...>
To: Ingo Molnar <mingo@...>
Cc: Arjan van de Ven <arjan@...>, <akpm@...>, <hugh@...>, <linux-mm@...>, <linux-kernel@...>, <briangrant@...>, <cgd@...>, <mbligh@...>, Linus Torvalds <torvalds@...>, Thomas Gleixner <tglx@...>, H. Peter Anvin <hpa@...>
Subject: Re: pthread_create() slow for many threads; also time to revisit 64b context switch optimization?
Date: Wednesday, August 13, 2008 - 11:55 am

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Ingo Molnar wrote:

Yes, as we both agree, there are still such machines out there.

The real problem is: what to do if somebody complains?  If we would have
the extra flag such people could be accommodated.  If there is no such
flag then distributions cannot just add the flag (it's part of the
kernel API) and they would be caught between a rock and a hard place.
Option #2 provides the biggest flexibility.

I upstream kernel truly doesn't care about such machines anymore there
are two options:

- - really do nothing at all

- - at least reserve a flag in case somebody wants/has to implement option
  #2

- --
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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Messages in current thread:
Re: pthread_create() slow for many threads; also time to rev..., Pardo, (Tue Aug 12, 8:45 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Wed Aug 13, 6:44 am)
Re: pthread_create() slow for many threads; also time to rev..., Arjan van de Ven, (Wed Aug 13, 9:35 am)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Wed Aug 13, 10:21 am)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Wed Aug 13, 10:25 am)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Wed Aug 13, 10:36 am)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Wed Aug 13, 11:10 am)
Re: pthread_create() slow for many threads; also time to rev..., Andi Kleen, (Wed Aug 13, 4:42 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Fri Aug 15, 8:43 am)
Re: pthread_create() slow for many threads; also time to rev..., Andi Kleen, (Fri Aug 15, 9:33 am)
Re: pthread_create() slow for many threads; also time to rev..., Andrew Morton, (Wed Aug 13, 4:56 pm)
Re: pthread_create() slow for many threads; also time to rev..., Andi Kleen, (Wed Aug 13, 5:46 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Wed Aug 13, 11:21 am)
Re: pthread_create() slow for many threads; also time to rev..., H. Peter Anvin, (Wed Aug 13, 12:05 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Wed Aug 13, 11:40 am)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Wed Aug 13, 11:55 am)
Re: pthread_create() slow for many threads; also time to rev..., Linus Torvalds, (Wed Aug 13, 1:09 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Wed Aug 13, 2:04 pm)
Re: pthread_create() slow for many threads; also time to rev..., Arjan van de Ven, (Wed Aug 13, 2:16 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Wed Aug 13, 2:22 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Wed Aug 13, 12:02 pm)
Re: pthread_create() slow for many threads; also time to rev..., Jamie Lokier, (Fri Aug 15, 11:54 am)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Fri Aug 15, 1:13 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Fri Aug 15, 1:19 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ulrich Drepper, (Fri Aug 15, 1:23 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Fri Aug 15, 3:00 pm)
Re: pthread_create() slow for many threads; also time to rev..., Ingo Molnar, (Fri Aug 15, 12:03 pm)