Date: Thu, 07 Mar 2002 17:20:45 -0500 (EST) From: John Baldwin <jhb@FreeBSD.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Julian Elischer <julian@elischer.org>, FreeBSD current users <current@FreeBSD.ORG>, Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp>, Bosko Milekic <bmilekic@unixdaemons.com>, Alfred Perlstein <alfred@FreeBSD.ORG>, Terry Lambert <tlambert2@mindspring.com>, Bruce Evans <bde@zeta.org.au>, "Jeroen C.van Gelderen" <jeroen@vangelderen.org> Subject: Re: Patch for critical_enter()/critical_exit() & interrupt assem Message-ID: <XFMail.020307172045.jhb@FreeBSD.org> In-Reply-To: <200203070318.g273IBB60433@apollo.backplane.com>
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On 07-Mar-02 Matthew Dillon wrote: > >:Search for "paper John Baldwin" and find link 6: >: >:http://www.FreeBSD.org/cgi/getmsg.cgi?fetch=199282+204026+/usr/local/www/db/ >:text/2002/freebsd-arch/20020303.freebsd-arch >: >:The actual paper is at: >: http://www.FreeBSD.org/~jhb/smpng/design/article.{ps,pdf} >: >:-J >:-- >:Jeroen C. van Gelderen - jeroen@vangelderen.org > > Ok... I've read it. The sections on interrupts and critical sections > are fully compatible with my patch. The one section... basically > the last sentence of the last paragraph, is exactly the piece that > my patch cleans up and makes more flexible. Instead of requiring that > cpu_critical_*() always be used for the initial critical_enter() my > patch makes it optional, and for I386 I use that flexibility to allow > critical_*() to NOT have to call cpu_critical_*(). You seemed to have missed the entire part where we handle deferred preemptions in MI code in critical_exit(). The critical_enter/exit stuff really exists to support the preemption code and to get rid of the various FOO_NOSWITCH flags. I think it is ok to remove the linkage between critical_enter/exit and cpu_critical_* (possibly even renaming cpu_critical_* to a better name) and to allow arch's to optimize cpu_critical_* but leave critical_* as MI code. That's what I've asked for from the start and Jake even suggested it from the start. I'm still not comfortable with the optimiation, but changing the MI critical_* code is by far my biggest objection to the code. > -Matt > Matthew Dillon > <dillon@backplane.com> -- 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-current" in the body of the message
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