Messages in this thread | | | Subject | Re: linux-kernel-digest V1 #2839 (writable /proc/<pid>/cmdli | Date | Wed, 25 Nov 1998 15:29:18 -0600 (EST) | From | kwrohrer@ce ... |
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And lo, Stephen C. Tweedie saith unto me: > On Tue, 17 Nov 1998 05:48:43 +0100, Andi Kleen <ak@muc.de> said: > > > If the threads share VM (with CLONE_VM) they share all memory, > > including the environment. argv[] is stored in the environment. > > Changing Linux to support only partly shared memory in CLONE_VM (with > > threads private pages like in Windows or OS/2) would be a fairly major > > redesign of the kernel threads mechanism. > > Not to mention that the performance would suck: currently we avoid any > flushing of the hardware task context when we switch between threads. > That would not be possible if the threads maintained their own page > tables. > > The best suggestion I've heard was to use the %fs register to maintain > a user-space pointer to thread-local storage. However, any access to > that space would be closely reliant on gcc extensions. If processes *really* need thread-local storage, they can make an array of pointers before they go thread-hot, then index on pthread_self(). So unless processes *really* need *protected* thread-local storage, this is a userspace problem anyway.
Keith
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