From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 10 Jul 2002 16:26:56 -0700 From: "Martin J. Bligh" Subject: Re: scalable kmap (was Re: vm lock contention reduction) Message-ID: <167170000.1026343616@flay> In-Reply-To: <3D2CBE6A.53A720A0@zip.com.au> References: <3D2BC6DB.B60E010D@zip.com.au> <91460000.1026341000@flay> <3D2CBE6A.53A720A0@zip.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Andrea Arcangeli , Linus Torvalds , Rik van Riel , "linux-mm@kvack.org" List-ID: > Yes, I've seen the in-kernel profiler doing odd things. If > you're not using the local APIC timer then I think the new > IRQ balancing code will break the profiler by steering the > clock interrupts away from busy CPUs (!). The first patch we apply is this diff -Nur linux-2.5.23-vanilla/arch/i386/kernel/io_apic.c linux-2.5.23-patched/arch/i386/kernel/io_apic.c --- linux-2.5.23-vanilla/arch/i386/kernel/io_apic.c Tue Jun 18 19:11:52 2002 +++ linux-2.5.23-patched/arch/i386/kernel/io_apic.c Thu Jun 27 14:28:51 2002 @@ -247,7 +247,7 @@ static inline void balance_irq(int irq) { -#if CONFIG_SMP +#if (CONFIG_SMP && !CONFIG_MULTIQUAD) irq_balance_t *entry = irq_balance + irq; unsigned long now = jiffies; Which should turn of IRQ balancing completely, I think ... > But ISTR that the profiler has gone whacky even with CONFIG_X86_LOCAL_APIC, > which shouldn't be affected by the IRQ steering. Interrupt 0 will only ever go the first quad (well, it should do if I actually fixed the timers), but CONFIG_X86_LOCAL_APIC=y is on. Wierd ... > But NMI-based oprofile is bang-on target so I recommend you use that. > I'll publish my oprofile-for-2.5 asap. That'd be good, but I'm not sure my box likes NMIs too much ;-) We'll see .... M. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/