From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 23 Aug 2002 16:41:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 23 Aug 2002 16:41:27 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:16118 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id ; Fri, 23 Aug 2002 16:41:26 -0400 Message-ID: <3D669ED1.402D1432@mvista.com> Date: Fri, 23 Aug 2002 13:45:05 -0700 From: george anzinger Organization: Monta Vista Software X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.2.12-20b i686) X-Accept-Language: en MIME-Version: 1.0 To: Robert Love CC: root@chaos.analogic.com, sanket rathi , linux-kernel@vger.kernel.org Subject: Re: interrupt handler References: <1030121541.1935.3684.camel@phantasy> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Robert Love wrote: > > On Fri, 2002-08-23 at 12:45, Richard B. Johnson wrote: > > > On 23 Aug 2002, Robert Love wrote: > > > Only the current interrupt handler is disabled... interrupts are > > > normally ON. > > > > No. Check out irq.c, line 446. The interrupts are turned back on > > only if the flag did not have SA_INTERRUPT set. Certainly most > > requests for interrupt services within drivers have SA_INTERRUPT > > set. > > Sigh... SA_INTERRUPT is used only for fast interrupts. Certainly most > drivers do not have it (and most that do are probably from the way old > days when we went through great pains to distinguish between fast and > slow interrupt handlers). > > Today, very few things should run with all interrupts disabled. That is > just dumb. In fact, on this system, it seems only the timer interrupt > sets SA_INTERRUPT... > And THAT makes sense as most of the timer interrupt is processed holding the write_lock() on xtime which would need to be an irq lock otherwise. If they were turned on the system would have an additional interrupts on/off overhead. > Robert Love > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml