From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 13 Jun 2000 23:46:13 -0300 (BRST) From: Rik van Riel Subject: Re: [patch] improve streaming I/O [bug in shrink_mmap()] In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: "Juan J. Quintela" , "Stephen C. Tweedie" , Zlatko Calusic , alan@redhat.com, Linux MM List , Linux Kernel List , Linus Torvalds List-ID: On Wed, 14 Jun 2000, Andrea Arcangeli wrote: > On Tue, 13 Jun 2000, Rik van Riel wrote: > >On Wed, 14 Jun 2000, Andrea Arcangeli wrote: > > > >> >and we can support all corner cases of usage well without it. In > >> >fact, as I demonstrated above, even your own contorted example will > >> >hang classzone if I only switch the order in which the allocations > >> >happen... > >> > >> It won't hang, but kswapd will eat CPU and that's right in your case. The > >> difference that you can't see is that in the second scenario where the > >> classzone would spend CPU in kswapd the CPU is spent for a purpose that > >> have a sense. In the first scenario where classzone wouldn't any spend > >> CPU, the CPU in kswapd would infact be _wasted_. > > > >Now explain to me *why* this happens. I'm pretty sure this happens > >because of the 'dispose = &old' in shrink_mmap and not because of > >anything even remotely classzone related... > > You waste CPU in kswapd in the first scenario simply because you > are not looking backwards at the ZONE_DMA state at the time you > have to choose if you did some progress on the ZONE_NORMAL zone. > > The problem isn't related to shrink_mmap, but only to the zone design > (proper classzone part). But when you switch around the order of allocation in your hypothetical example, allocating the cache first, from the ZONE_NORMAL and then proceeding to mlock the rest of the normal zone and the dma zone, then classzone will still break. > >I'm trying to improve the Linux kernel here, I'd appreciate it if > >you were honest with me. > > Are you saying I'm not been honest with you? JFYI: I don't enjoy to get > insulted by you (and it's not the first time). I will ignore also your > above comment but please don't insult me anymore in the future! Thanks. Conveniently snipping out the part of my post where I proved your example wrong is not what I'd call constructive dialog. Maybe the "honesty" thing was a bit much. I should get some sleep and try again tomorrow using less inflammatory words. regards, Rik -- The Internet is not a network of computers. It is a network of people. That is its real strength. Wanna talk about the kernel? irc.openprojects.net / #kernelnewbies http://www.conectiva.com/ http://www.surriel.com/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/