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Re: cvs commit: src/sys/i386/include tls.h src/gnu/usr.bin/cc34/cc_prep/config dragonfly-spec.h src/gnu/usr.bin/cc34/cc_prep/config/i386 dragonfly.h src/lib/csu/i386 crt1.c src/lib/libc/gen tls.c src/lib/libc/i386/sys cerror.S src/lib/libc/include libc_private.h ...

From: David Xu <davidxu@xxxxxxxxxxx>
Date: Thu, 12 May 2005 14:37:41 +0800

Matthew Dillon wrote:
:I need fast critical section, otherwise I can just use sigprocmask
:everywhere, the critical section has to be per-thread based, a
:shared memory page won't work. one thread blocking signal shouldn't
:stop other threads to process signal.
:David Xu

    Well, each thread could have its own block of memory.  But that could
    add up fairly quickly.

I don't think it is cheap on x86 architecture.

    A TCB based critical section is certainly reasonable, and easy for the
    kernel to access.

    Another option would be to implement a code path critical section.
    Basically we would inform the kernel not to interrupt userland if
    the userland instruction pointer is within a specified range of
    addresses.  This would also be easy to implement.

I don't like the idea. Thread library also wants to use the critical
region, and maybe .mcount() based profiling code also wants this.

Matthew Dillon <dillon@xxxxxxxxxxxxx>

David Xu

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