From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gabriel Paubert Date: Mon, 28 Apr 2003 10:53:42 +0200 To: Paul Mackerras Cc: Fred Gray , linuxppc-dev@lists.linuxppc.org Subject: Re: ppc_irq_dispatch_handler dominating profile? Message-ID: <20030428085342.GA7396@iram.es> References: <20030427194236.GC25907@socrates.berkeley.edu> <16044.23965.747962.112267@nanango.paulus.ozlabs.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <16044.23965.747962.112267@nanango.paulus.ozlabs.org> Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: On Mon, Apr 28, 2003 at 08:45:49AM +1000, Paul Mackerras wrote: > > Fred Gray writes: > > > In both cases, ppc_irq_dispatch_handler is the "winner." I'm not very familiar > > with the kernel profiler, especially on the PowerPC, so I don't know whether > > or not this is likely to be an artifact of piled-up timer interrupts. > > Otherwise, it suggests that something dramatically inefficient is > > happening in the interrupt handling chain, since it spends twice as much > > time here as it does touching all of the outgoing data for the copy and > > checksum. > > ppc_irq_dispatch_handler is the first place where interrupts get > turned on in the interrupt handling path, so all the time spent saving > registers and finding out which interrupt occurred gets attributed to > it. > > How many interrupts per second are you handling? A 200MHz 604e isn't > a fast processor by today's standards. Also, how fast is your memory > system? I would be a little surprised if the memory controller could > deliver any more than about 100MB/s. Hmmm, I get more than 100MB/s on my MVME2600 with a 200MHz 603e, although not the half GB/s Motorola claims it is capable of. But a 604 should be a bit faster. The chipset is old (1997) but it was rather fast when it came out, especially because the memory interface is 128 bits wide. This said, putting a gbit Ethernet (PMC module I suppose) on it is stretching it a bit. Is the 100Mb/s of the builtin interface too slow for you? Gabriel. ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/