From mboxrd@z Thu Jan 1 00:00:00 1970 From: tom_gall@vnet.ibm.com Message-ID: <399ABFBE.7278954E@vnet.ibm.com> Date: Wed, 16 Aug 2000 16:22:22 +0000 Reply-To: tom_gall@vnet.ibm.com MIME-Version: 1.0 To: Graham Stoney CC: dan@netx4.com, linuxppc-dev@lists.linuxppc.org Subject: Re: Help with string.S References: <399A4220.23A3B0F5@research.canon.com.au> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-dev@lists.linuxppc.org List-Id: Graham Stoney wrote: > > Casting our minds back to July, Dan Malek wrote: > > OK, I think I am bailing out here. For some reason, if I remove > > the 'dcbz' instructions on the MPC8xx processor the world is just > > a better place. I don't know why, maybe because of some of the > > TLB mapping, but I can't find a reason. > > What was the eventual outcome of this? I've been doing some 2.2.13 > kernel profiling on the 860, and __copy_tofrom_user is coming up as a > hotspot. > I tried dropping in the new improved version from > linux-2.4.0-test7-pre4, and none of the 8xx mods are in there: it'l only > work for 32 byte cache lines. Graham, That's not right. Which version of linux-2.4.0-x do you have? I'm sure Paul's, Cort's and and I know for sure mine work for more than 32 byte cache lines because 2 of my boxes have 128 byte cache lines and there's support in there for it. (Paul wrote it... awesome stuff) > I hacked it around and found the same as you: it won't work with the > dcbz in there, and of course it doesn't run any faster than the old > version without it. It's certainly getting more complex in there, and I > see your point about whether the extra code will actually make it run > any faster, especially on 8xx CPUs with small I-caches. I'd be keen to > test whatever you've come up with to see if it's actually better than > the old 2.2 code on 8xx CPUs. This isn't the only spot too by the way ... glibc has the some problem. > It sounds like a few people have at least had a shot at adding support > for other than 32 byte cache lines, but none have propagated into the > official kernels; how does that happen anyway? By official are you meaning Linus' ? Regards, Tom -- Tom Gall - PowerPC Linux Team "Where's the ka-boom? There was Linux Technology Center supposed to be an earth (w) tom_gall@vnet.ibm.com shattering ka-boom!" (w) 507-253-4558 -- Marvin Martian (h) tgall@uswest.net http://oss.software.ibm.com/developerworks/opensource/linux ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/