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

Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]
From: Ingo Molnar
Date: Wednesday, August 13, 2008 - 9:02 am

* Ulrich Drepper <drepper@redhat.com> wrote:


do nothing at all is not an option - thread creation can take 10 msecs 
on top-of-the-line hardware.


yeah, i already had a patch for that when i wrote my first mail 
[attached below] and listed it as option #4 - then erased the comment 
figuring that we'd want to do #1 ;-)

As unimplemented flags just get ignored by the kernel, if this flag goes 
into v2.6.27 as-is and is ignored by the kernel (i.e. we just use a 
plain old 64-bit [47-bit] allocation), then you could do the glibc 
change straight away, correct? So then if people complain we can fix it 
in the kernel purely.

how about this then?

	Ingo

--------------------->
Subject: mmap: add MAP_64BIT_STACK
From: Ingo Molnar <mingo@elte.hu>
Date: Wed Aug 13 12:41:54 CEST 2008

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 include/asm-x86/mman.h |    1 +
 1 file changed, 1 insertion(+)

Index: linux/include/asm-x86/mman.h
===================================================================
--- linux.orig/include/asm-x86/mman.h
+++ linux/include/asm-x86/mman.h
@@ -12,6 +12,7 @@
 #define MAP_NORESERVE	0x4000		/* don't check for reservations */
 #define MAP_POPULATE	0x8000		/* populate (prefault) pagetables */
 #define MAP_NONBLOCK	0x10000		/* do not block on IO */
+#define MAP_64BIT_STACK	0x20000		/* give out 32bit addresses on old CPUs */
 
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */

--
Previous message: [thread] [date] [author]
Next message: [thread] [date] [author]

Messages in current thread:
Re: pthread_create() slow for many threads; also time to r ..., Ingo Molnar, (Wed Aug 13, 9:02 am)
Re: pthread_create() slow for many threads; also time to r ..., Arjan van de Ven, (Wed Aug 13, 11:16 am)