From mboxrd@z Thu Jan 1 00:00:00 1970 MIME-Version: 1.0 In-Reply-To: References: <201102181445.41877.dexen.devries@gmail.com> <201102181753.30125.dexen.devries@gmail.com> Date: Fri, 18 Feb 2011 12:16:41 -0500 Message-ID: Subject: Re: [9fans] Modern development language for Plan 9, WAS: Re: RESOLVED: recoving important header file rudely From: Russ Cox To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Cc: erik quanstrom Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Topicbox-Message-UUID: b0d25cc8-ead6-11e9-9d60-3106f5b1d025 On Fri, Feb 18, 2011 at 12:07 PM, erik quanstrom wr= ote: >> The high level overview is that it is stored in a shared page, mapped >> into each new process's memory space at start-up. The kernel is never >> entered; there are no context switches. The kernel has a timer that >> updates this page atomically. > > i wonder if that is uniformly faster. =C2=A0consider that > making reads of that page coherent enough on a > big multiprocessor and making sure there's not too > much interprocesser skew might be slower than a > system call. are you claiming that enter system call look at kernel data page to figure out time exit system call could be faster than look at kernel data page to figure out time ? either way the memory accesses in the middle are the same.