From mboxrd@z Thu Jan 1 00:00:00 1970 From: erik quanstrom Date: Mon, 23 Sep 2013 09:56:51 -0400 To: 9fans@9fans.net Message-ID: <3ddf9699caf0ffcff5ebb9f50b49f996@brasstown.quanstro.net> In-Reply-To: References: <64cc61c082febe489ac3244473bb4ca4@brasstown.quanstro.net> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Subject: Re: [9fans] userspace semlocks Topicbox-Message-UUID: 80eb51ca-ead8-11e9-9d60-3106f5b1d025 > you are missing the reason. read the paper. the paper in question one assumes is "Semaphores in Plan 9", Sape Mullender and Russ Cox, IWP9, 2008. the idea in the paper is the scheduler might hurt, but i don't think there's any real development of that idea. so it's also possible that the scheduler might not hurt due to some interactions not discussed. it's also possible that the implementation of semaphores, which requires two locks in the kernel contended case, and always requires two calls to seg and validaddr is slower than the old method of sleep(0). and finally, it's difficult to explain why my results do not square with Table 2. - erik