From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <3C179431.8AE76198@strakt.com> From: Boyd Roberts MIME-Version: 1.0 To: 9fans@cse.psu.edu Subject: Re: [9fans] RDMA: DMA over TCP/IP at IETF References: <20011212134632.4659619A0B@mail.cse.psu.edu> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Date: Wed, 12 Dec 2001 18:30:25 +0100 Topicbox-Message-UUID: 3449d21e-eaca-11e9-9e20-41e7f4b1d025 rob pike wrote: > > If I recall correctly, "IIRC" is a shorthand for "if I recall correctly", > and either you don't or I don't. http://plan9.bell-labs.com/sys/doc/sleep.html: The mistake is that the reading of r->p may occur just as the other process calls sleep, so when the interrupt examines the structure it sees no one to wake up, and the sleeping process misses its wakeup. We wrote the code this way because we reasoned that the fetch p = r->p was inherently atomic and need not be interlocked. The bug was found by examination when a new, very fast device was added to the system and sleeps and interrupts were closely overlapped. However, it was in the system for a couple of months without causing an error. > Nowadays, Holzmann's stuff is applied directly to the kernel > sources, which helps a lot. spin [Holzmann's stuff] is a really neat idea.