[Spice-devel] [PATCH 1/5] use _setjmp/_longjmp to speed up coroutine switching

[Christophe Fergeau]

Hey,

ACK series, but I haven't read the winfiber code really carefully (since I
know nothing about it).

Christophe

On Wed, Aug 17, 2011 at 02:45:11PM +0200, Marc-André Lureau wrote:
> As described in http://www.1024cores.net/home/lock-free-algorithms/tricks/fibers
> ---
>  gtk/continuation.c |   12 +++++++++++-
>  gtk/continuation.h |    2 ++
>  2 files changed, 13 insertions(+), 1 deletions(-)
> 
> diff --git a/gtk/continuation.c b/gtk/continuation.c
> index 4f5b027..6eaed3c 100644
> --- a/gtk/continuation.c
> +++ b/gtk/continuation.c
> @@ -21,6 +21,7 @@
>  #include <config.h>
>  
>  #include "continuation.h"
> +#undef _FORTIFY_SOURCE
>  
>  /*
>   * va_args to makecontext() must be type 'int', so passing
> @@ -40,6 +41,11 @@ static void continuation_trampoline(int i0, int i1)
>  	arg.i[1] = i1;
>  	cc = arg.p;
>  
> +	if (_setjmp(cc->jmp) == 0) {
> +		ucontext_t tmp;
> +		swapcontext(&tmp, &cc->last);
> +	}
> +
>  	cc->entry(cc);
>  }
>  
> @@ -56,6 +62,7 @@ int cc_init(struct continuation *cc)
>  	cc->uc.uc_stack.ss_flags = 0;
>  
>  	makecontext(&cc->uc, (void *)continuation_trampoline, 2, arg.i[0], arg.i[1]);
> +	swapcontext(&cc->last, &cc->uc);
>  
>  	return 0;
>  }
> @@ -78,7 +85,10 @@ int cc_swap(struct continuation *from, struct continuation *to)
>  	else if (to->exited == 1)
>  		return 1;
>  
> -	return swapcontext(&from->uc, &to->uc);
> +	if (_setjmp(from->jmp) == 0)
> +		_longjmp(to->jmp, 1);
> +
> +	return 0;
>  }
>  /*
>   * Local variables:
> diff --git a/gtk/continuation.h b/gtk/continuation.h
> index 87cd4ee..1247337 100644
> --- a/gtk/continuation.h
> +++ b/gtk/continuation.h
> @@ -23,6 +23,7 @@
>  
>  #include <stddef.h>
>  #include <ucontext.h>
> +#include <setjmp.h>
>  
>  struct continuation
>  {
> @@ -35,6 +36,7 @@ struct continuation
>  	ucontext_t uc;
>  	ucontext_t last;
>  	int exited;
> +	jmp_buf jmp;
>  };
>  
>  int cc_init(struct continuation *cc);
> -- 
> 1.7.6
> 
> _______________________________________________
> Spice-devel mailing list
> Spice-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/spice-devel
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