* [Bug libc/207] ucontext is very slow.
2004-06-07 8:45 [Bug libc/207] New: ucontext is very slow a dot darovskikh at compassplus dot ru
@ 2004-06-07 8:47 ` a dot darovskikh at compassplus dot ru
2004-06-07 8:48 ` a dot darovskikh at compassplus dot ru
` (3 subsequent siblings)
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From: a dot darovskikh at compassplus dot ru @ 2004-06-07 8:47 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From a dot darovskikh at compassplus dot ru 2004-06-07 08:47 -------
Created an attachment (id=106)
--> (http://sources.redhat.com/bugzilla/attachment.cgi?id=106&action=view)
A windows test case
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* [Bug libc/207] ucontext is very slow.
2004-06-07 8:45 [Bug libc/207] New: ucontext is very slow a dot darovskikh at compassplus dot ru
2004-06-07 8:47 ` [Bug libc/207] " a dot darovskikh at compassplus dot ru
@ 2004-06-07 8:48 ` a dot darovskikh at compassplus dot ru
2004-06-08 14:57 ` jakub at redhat dot com
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: a dot darovskikh at compassplus dot ru @ 2004-06-07 8:48 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From a dot darovskikh at compassplus dot ru 2004-06-07 08:48 -------
Created an attachment (id=107)
--> (http://sources.redhat.com/bugzilla/attachment.cgi?id=107&action=view)
A unix ucontext test case
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* [Bug libc/207] ucontext is very slow.
2004-06-07 8:45 [Bug libc/207] New: ucontext is very slow a dot darovskikh at compassplus dot ru
2004-06-07 8:47 ` [Bug libc/207] " a dot darovskikh at compassplus dot ru
2004-06-07 8:48 ` a dot darovskikh at compassplus dot ru
@ 2004-06-08 14:57 ` jakub at redhat dot com
2004-06-09 4:31 ` a dot darovskikh at compassplus dot ru
2004-08-10 2:06 ` drepper at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: jakub at redhat dot com @ 2004-06-08 14:57 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From jakub at redhat dot com 2004-06-08 14:38 -------
Hardly.
More than 50% of the time is spent in sigprocmask syscalls, which are needed
(the program can change its signal mask any time and this needs to be preserved,
caching current signal mask in userland would be a huge can of problems and
slowdowns for little gain).
The other big part of the total time is spent on saving/restoring FPU state
(again, swapcontext must do this) and that's about it.
Why aren't you using real threads instead?
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* [Bug libc/207] ucontext is very slow.
2004-06-07 8:45 [Bug libc/207] New: ucontext is very slow a dot darovskikh at compassplus dot ru
` (2 preceding siblings ...)
2004-06-08 14:57 ` jakub at redhat dot com
@ 2004-06-09 4:31 ` a dot darovskikh at compassplus dot ru
2004-08-10 2:06 ` drepper at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: a dot darovskikh at compassplus dot ru @ 2004-06-09 4:31 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From a dot darovskikh at compassplus dot ru 2004-06-09 04:30 -------
Subject: Re: ucontext is very slow.
On Tuesday 08 June 2004 20:38, jakub at redhat dot com wrote:
> ------- Additional Comments From jakub at redhat dot com 2004-06-08 14:38
> ------- Hardly.
> More than 50% of the time is spent in sigprocmask syscalls, which are
> needed (the program can change its signal mask any time and this needs to
> be preserved, caching current signal mask in userland would be a huge can
> of problems and slowdowns for little gain).
> The other big part of the total time is spent on saving/restoring FPU state
> (again, swapcontext must do this) and that's about it.
>
> Why aren't you using real threads instead?
This is because we use thousands so-called "tasks", which access on the same
"tree". If we implement it using real threads, they will use complex
synchronization, which will take much more time than the real work. This is
why we need cooperative multitasking. There are some more complex reasons for
this, so I'm afraid, we will not able to use real threads. Indeed, we do use
it, but it's for external things, like database connections.
Is it possible to avoid sigprocmask syscalls and FPU things? We do not use it.
Maybe it's possible to take this code and remove those calls from it? Or use
something like setjmp/longjmp? I tried last one, but timings were even worse.
Alexander Darovsky.
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* [Bug libc/207] ucontext is very slow.
2004-06-07 8:45 [Bug libc/207] New: ucontext is very slow a dot darovskikh at compassplus dot ru
` (3 preceding siblings ...)
2004-06-09 4:31 ` a dot darovskikh at compassplus dot ru
@ 2004-08-10 2:06 ` drepper at redhat dot com
4 siblings, 0 replies; 6+ messages in thread
From: drepper at redhat dot com @ 2004-08-10 2:06 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From drepper at redhat dot com 2004-08-10 02:06 -------
The functions already do the minimal amount of work. There are no speedups
possible. Create your own library with specialized code which does not have to
be general if you don't like it.
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Status|WAITING |RESOLVED
Resolution| |WONTFIX
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