From owner-freebsd-current Sat Aug 10 11:48: 7 2002 Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EFC8137B400 for ; Sat, 10 Aug 2002 11:48:05 -0700 (PDT) Received: from gull.mail.pas.earthlink.net (gull.mail.pas.earthlink.net [207.217.120.84]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6CA8F43E6A for ; Sat, 10 Aug 2002 11:48:05 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from pool0086.cvx21-bradley.dialup.earthlink.net ([209.179.192.86] helo=mindspring.com) by gull.mail.pas.earthlink.net with esmtp (Exim 3.33 #1) id 17dbHO-0007fX-00; Sat, 10 Aug 2002 11:48:02 -0700 Message-ID: <3D555FAD.A4137491@mindspring.com> Date: Sat, 10 Aug 2002 11:47:09 -0700 From: Terry Lambert X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Bruce Evans Cc: Maksim Yevmenkin , current@FreeBSD.ORG Subject: Re: Interrupt vs. polling on -current References: <20020810192039.E16346-100000@gamplex.bde.org> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Bruce Evans wrote: > No, but the 3Com driver apparently is. The sio driver wants to have > fast interrupts. It can't have them with the irq is shared, so its > worst-case interrupt latency for a single serial port is increased > from about 50 usec to many msec, depending other interrupt activity > in the system (not limited to that for the shared irq except in some > configurations). Silo overflows occur at 115200 bps when the latency > is more than about 1.5 msec. Anyway to get the code to complain about the sharing of serial interrupts? Also, if there is a PCI interrupt for the serial (serial handled by Northbridge... I'd like to see this, actually), shouldn't it be capable of sharing *only* fast interrupts somehow? It's an obvious pessimization to mix other interrupts with fast interrupts, but less obvious what would happen with fast + fast... > FreeBSD on a 486/33 can handle about 40000 serial interrupts per second > to do one character of i/o per interrupt). Pessimizations in -current > have only degraded this by a small factor (2?), provided the driver > uses fast interrupts. Lose another small factor (2?) for normal interrupts > (using normal interrupts only loses a large factor for latency). Any way to fix this, short of "don't run -current"?? Thanks, -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message