From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <391BEAED.C9313263@sympatico.ca> Date: Fri, 12 May 2000 07:28:45 -0400 From: John Cavan MIME-Version: 1.0 Subject: Re: PATCH: rewrite of invalidate_inode_pages References: <14619.16278.813629.967654@charged.uio.no> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: "Juan J. Quintela" Cc: trond.myklebust@fys.uio.no, Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.rutgers.edu List-ID: I'm by no means an expert in this, I just follow the list to learn, but would it not be possible to make ITERATIONS count a runtime configurable parameter in the /proc filesystem that defaults to 100? That would allow for the best tuning scenario for a given system. Just a thought. John Cavan "Juan J. Quintela" wrote: > > >>>>> "trond" == Trond Myklebust writes: > > >>>>> " " == Juan J Quintela writes: > >> Then you want only invalidate the non_locked pages: do you > > trond> That's right. This patch looks much more appropriate. > > >> + while (count == ITERATIONS) { > >> + spin_lock(&pagecache_lock); > >> + spin_lock(&pagemap_lru_lock); > >> + head = &inode->i_mapping->pages; > >> + curr = head->next; > >> + count = 0; > >> + > >> + while ((curr != head) && (count++ < ITERATIONS)) { > > trond> Just one question: Isn't it better to do it all in 1 iteration through > trond> the loop rather than doing it in batches of 100 pages? > trond> You can argue that you're freeing up the spinlocks for the duration of > trond> the loop_and_test, but is that really going to make a huge difference > trond> to SMP performance? > > Trond, I have not an SMP machine (yet), and I can not tell you numbers > now. I put the counter there to show that we *may* want to limit the > latency there. I am thinking in the write of a big file, that can > take a lot to free all the pages, but I don't know, *you* are the NFS > expert, this was one of the reasons that we want feedback from the > users of the call. (You have been very good giving comments). > > My idea to put a limit is to put a limit than normally you do all in > one iteration, but in the exceptional case of a big amount of pages, > the latency is limited. There is a limit in the number of pages that > can be in that list? > > 100 is one number that can need tuning, I don't know. SMP experts > anywhere? > > By the way, while we are here, the only difference between > truncate_inode_pages and invalidate_inode_pages is the one that you > told here before? I am documenting some of the MM stuff, and your > comments in that aspect are really wellcome. (You will have noted > now that I am quite newbie here). > > Later, Juan. > > -- > In theory, practice and theory are the same, but in practice they > are different -- Larry McVoy > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.rutgers.edu > Please read the FAQ at http://www.tux.org/lkml/ -- 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/