Date: Thu, 19 Oct 1995 15:58:57 PDT From: "Marty Leisner" <leisner@sdsp.mc.xerox.com> To: Julian Elischer <julian@ref.tfs.com> Cc: cimaxp1!jb@werple.net.au (John Birrell), mira!sdsp.mc.xerox.com!leisner@werple.net.au, hackers@freebsd.org, jb@cimlogic.com.au Subject: Re: NetBSD/FreeBSD (pthreads) Message-ID: <9510192300.AA03362@willow.mc.xerox.com> In-Reply-To: Your message of "Thu, 19 Oct 1995 15:46:19 PDT." <199510192246.PAA23918@ref.tfs.com>
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In message <199510192246.PAA23918@ref.tfs.com>, you write: >> I'm curious about why you *need* kernel threads. > >usually it's for several blocking IO streams.. > pthreads handles this... But it does this via (I think...) all I/O being nonblocking, and if it would block it then run another thread.... I haven't looked at the code for a while, but kernel threads would be much more efficient (if a task blocks on I/O, it blocks inside the kernel, rather then muxing on select...) I agree you can implement user-space pthreads efficiently if multiple processor are compute bound...but this is not why you have threads... Also, each kernel call will need context switches, which slow things down... marty
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