Date: Mon, 26 Jan 2004 15:46:41 -0500 From: John Baldwin <jhb@FreeBSD.org> To: Jeff Roberson <jroberson@chesapeake.net> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/i386 local_apic.c Message-ID: <200401261546.41842.jhb@FreeBSD.org> In-Reply-To: <20040126150636.E36463-100000@mail.chesapeake.net> References: <20040126150636.E36463-100000@mail.chesapeake.net>
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On Monday 26 January 2004 03:08 pm, Jeff Roberson wrote: > On Mon, 26 Jan 2004, John Baldwin wrote: > > On Sunday 25 January 2004 12:03 am, Jeff Roberson wrote: > > > jeff 2004/01/24 21:03:14 PST > > > > > > FreeBSD src repository > > > > > > Modified files: > > > sys/i386/i386 local_apic.c > > > Log: > > > - Don't define DETECT_DEADLOCK. I don't know that this code has > > > detected a deadlock in several years. Furthermore, the IPI code is > > > currently protected by a seperate spinlock. This only served to make > > > IPIs twice as expensive as they had to be which severely slowed down > > > the IPI heavy ULE scheduler. > > > > What spinlock? > > Er, based on earlier conversations with you I was under the assumption > that there was a lock around all of the ipi sender code. I must have this > confused with something else. Ah, ok. > > > grep mtx local_apic.c | wc -l > > > > 0 > > > > Some users of the ipi API use a spinlock themselves, but not all, and > > there certainly isn't a global ipi spin lock. According to witness, only > > sparc64 has an ipi spin lock. It might still be a good idea to turn this > > off or perhaps at least half of it. We will lose ipi's on non-XAPIC > > systems if you don't wait for the delivery status to clear before sending > > an IPI. Have you tested this on Pentium II's or earlier? > > My original patch did still poll before transmit. I'll correct this. Thanks. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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