Date: Wed, 2 Apr 2003 18:39:33 -0500 (EST) From: Jeff Roberson <jroberson@chesapeake.net> To: Terry Lambert <tlambert2@mindspring.com> Cc: current@freebsd.org Subject: Re: libthr and 1:1 threading. Message-ID: <20030402183406.O64602-100000@mail.chesapeake.net> In-Reply-To: <3E8B72C2.343AAEBD@mindspring.com>
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On Wed, 2 Apr 2003, Terry Lambert wrote: > Peter Wemm wrote: > > No. It gives the ability for a thread to block on a syscall without > > stalling the entire system. Just try using mysqld on a system using libc_r > > and heavy disk IO. You can't select() on a read() from disk. Thats the > > ultimate reason to do it. The SMP parallelism is a bonus. > > Bug in FreeBSD's NBIO implementation. A read() that would result > in page-in needs to queue the request, but return EAGAIN to user > space to indicate the request cannot be satisfied. Making select() > come true for disk I/O after the fault is satisfied is a seperate > issue. Probably need to pass the fd all the way down. > Please quote the standard that defines this behavior. This is entirely counter to everything that I have ever read on the subject.
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