From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH 2.6]: Make packet scheduler clock source configurable Date: Sat, 24 Jul 2004 01:18:50 +0200 Sender: netdev-bounce@oss.sgi.com Message-ID: <41019CDA.9050401@trash.net> References: <40F34740.5040100@trash.net> <1107.63.170.215.71.1089689716.squirrel@www.osdl.org> <20040712205037.573411c0.davem@redhat.com> <40F4862D.3070802@trash.net> <40F4AC8B.40706@trash.net> <20040721143110.4ab944bf.davem@redhat.com> <41004F76.1080807@trash.net> <20040722171752.341d2476.davem@redhat.com> <41006150.9000702@trash.net> <41014788.4070301@trash.net> <20040723135459.2ee5c42c.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: shemminger@osdl.org, netdev@oss.sgi.com, devik@cdi.cz Return-path: To: "David S. Miller" In-Reply-To: <20040723135459.2ee5c42c.davem@redhat.com> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org David S. Miller wrote: > We can't use this stuff on Alpha, it's cycle counter overflows after > just 10 minutes. It works very strangely, something like only the > lower 32-bits are guarenteed to be continually incrementing. The code (although racy) can handle 32-bit cycle counters. get_cycles() on alpha returns a 32-bit value, so psched_tick calls PSCHED_GET_TIME to adjust psched_time_base once a second. It is basically the same as before. This is the second condition for this too work, besides get_cycles() incrementing at >1MHz, it needs to return either a 32-bit value and really use the full 32 bit or return something bigger, which is assumed not to overflow. Alpha seems to satisfy both conditions. > I'm going to apply your patch and delete the Alpha parts. > Meanwhile, ping Richard Henderson (rth@redhat.com) or one > of the other Alpha experts for me to get confirmation on > this stuff. Even better. Regards Patrick