Date: Wed, 2 Apr 2003 16:26:26 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: Peter Wemm <peter@wemm.org> Cc: current@freebsd.org Subject: Re: libthr and 1:1 threading. Message-ID: <200304030026.h330QQbH087256@apollo.backplane.com> References: <20030403000816.AEB842A8A7@canning.wemm.org>
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That's a cute trick. The ultimate solution is to implement
a semi-synchronous message passing API to replace the myrid
system calls we have now. Roughly speaking, what the Amiga
did for messages, ports, and I/O, is far superior then what
is done in Linux and *BSD. You get the benefit of being able
to operate syncnronously when possible, and having a convenient
cup-holder for the operation state if you decide you have to
'block' the operation (instead of the state being strewn
all over the call stack in a syscall implementation). Userland
can decide whether to block or not block on an operation
entirely independant of the OS deciding whether to block or not
block on an operation.
-Matt
Matthew Dillon
<dillon@backplane.com>
:Without wanting to get too far off into the weeds, squid does something
:interesting. They need to be able to nonblock for everything including
:open(), read(), unlink(), readdir() etc. So what they do is implement a
:fairly significant superset of the traditional AIO stuff using pthreads. It
:seems to work pretty well for them, even with linuxthreads style threads.
:Granted, squid's needs are not exactly typical. But I did want to point
:out that a good part of the delays come not only from data IO but operations
:like opening a file (pathname traversal), creating or removing a file,
:reading a directory etc. This is a particular problem when the disk
:is really busy.
:
:Cheers,
:-Peter
:--
:Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
:"All of this is for nothing if we don't go to the stars" - JMS/B5
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