From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Tue, 04 Dec 2001 19:56:33 +0000 Subject: Re: [Linux-ia64] patch to no longer use ia64's software mmu Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Tue, 4 Dec 2001 17:18:17 +0000 (GMT), Alan Cox said: >> I think the issue at hand is whether, longer term, it is >> desirable to move all bounce buffer handling into the PCI DMA >> layer or whether Linux should continue to make bounce buffer >> management visible to drivers. I'd be interested in hearing >> opinions. Alan> I think the performance figures we see currently answer that Alan> already. The numbers I have seen so far don't make this obvious. Tony Luck reports 95Mbps with a CPU load of 20% after a fixing a performance bug in the software I/O TLB. Arjan reported the same 95Mbps figure with the highmem approach. Arjan didn't report the CPU load and neither Tony nor Arjan specified the test environment they were using. Alan> IA64 also needs to correct its GFP_DMA to mean "low 16Mb" for Alan> ISA DMA. While there is no ISA DMA on ia64 (thankfully) many Alan> PCI cards have 26-31 bit limits. We could do this if we there was a GFP_4GB zone. Now that 2.5 is open for business, it won't be long, right? --david