Re: horrible disk thorughput on itanium

[Padraig Brady <padraig@antefacto.com>]

Michael Poole wrote:

> Padraig Brady <padraig@antefacto.com> writes:
> 
> 
>>This breaks for the case discussed @
>>http://sources.redhat.com/ml/bug-glibc/2001-11/msg00079.html
>>I.E. if you have a multithreaded lib being linked by
>>single threaded apps (Note multithreaded lib, not just a
>>threadsafe lib (I.E. the lib calls pthread_create())).
>>
> 
> That's an interesting, but very contrived, example.  Can you find a
> single multi-threaded lib that uses FILE*'s shared with the
> application using it?


Well you have to deal with the general case. A single threaded

app linking against a multithreaded lib. It mightn't be just
shared FILE*'s that could cause problems.


> Linus's suggestion to add hooks to pthread_create() gets around that
> problem, anyway.


I don't think this will work as I said before current apps that
use _unlocked() functions directly manipulate the stdio structures,
hence a "new smarter locking stdio" would never get used by existing
compiled apps.

> Alternatively, the multi-threaded library could
> require any application linking to it to define _REENTRANT.


It could, but what if an existing interface (lib) is changed

from signle to multithreaded. You can't preclude this.


> After all, it's silly to talk about a 'multi-threaded' library linked
> to a 'single-threaded' application -- the application plus any
> libraries, as a whole, are either multithreaded or not.  They have to
> be on the same page to deal with *any* locking issues.
> 
> -- Michael

Padraig.