Re: horrible disk thorughput on itanium

[Padraig Brady <padraig@antefacto.com>]

Linus Torvalds wrote:

> On Fri, 7 Dec 2001, Andi Kleen wrote:
> 
>>Your proposals sound rather dangerous. They would silently break recompiled
>>threaded programs that need the locking and don't use -D__REENTRANT
>>
> 
> No it wouldn't.
> 
> Once you do a pthread_create(), the locking is there.
> 
> Before you do a pthread_create(), it doesn't lock.
> 
> What's the problem? Before you do a pthread_create(), you don't _NEED_
> locking, because there is only one thread that accesses the stdio data
> structures.
> 
> And there are no races - if there is only one thread, then another thread
> couldn't be suddenly doing a pthread_create() during a stdio operations.
> 
> Safe, and efficient. Yes, it adds a flag test or a indirect branch, but
> considering that you avoid a serialized locking instruction, the
> optimization sounds obvious.
> 
> 		Linus