Date: Thu, 05 Sep 2002 11:22:19 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Jan Lentfer <Jan.Lentfer@web.de> Cc: freebsd-alpha@FreeBSD.org, Andrew Gallatin <gallatin@cs.duke.edu>, ticso@cicely.de Subject: Re: alpha performance on -current Message-ID: <XFMail.20020905112219.jhb@FreeBSD.org> In-Reply-To: <1031238584.2988.14.camel@jan-linux.lan>
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On 05-Sep-2002 Jan Lentfer wrote: > Am Don, 2002-09-05 um 16.51 schrieb Bernd Walter: >> On Thu, Sep 05, 2002 at 10:43:27AM -0400, John Baldwin wrote: >> > >> > On 05-Sep-2002 Andrew Gallatin wrote: >> > > I'm using the appended diff, which I think is what you're suggesting: >> > >> > I think what he is really suggesting is to remove the mb's from all the >> > atomic_foo ops that don't have _acq or _rel in them. The _acq and _rel >> > versions should be wrappers that add mb's. >> >> Exactly. > > OK, I didn't get anything from the first sentence until now. What the > heck are you guys talking about??? I mean it, could someone explain or > even better point me to some resources so I can actually understand what > you guys mean? This is about kernel design and memory managment, right? > Any recommended readings? > > Thanks a lot in advance, This is about implementing atomic operations on Alpha CPU's for use by the kernel. You can read the atomic(9) man page on current for more info about this. An atomic operation just guarantees that the operation it is performing is atomic, hence the fact that normal atomic_foo() oops don't need memory barriers. Only the versions of atomic ops (such as atomic_foo_acq() or atomic_foo_rel()) require that memory barriers be used to guarantee specific ordering restraints. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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