From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id CFF3E5F0001 for ; Mon, 20 Apr 2009 16:32:12 -0400 (EDT) Date: Mon, 20 Apr 2009 22:31:19 +0200 From: Johannes Weiner Subject: Re: [patch 3/3][rfc] vmscan: batched swap slot allocation Message-ID: <20090420203119.GA26066@cmpxchg.org> References: <1240259085-25872-1-git-send-email-hannes@cmpxchg.org> <1240259085-25872-3-git-send-email-hannes@cmpxchg.org> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="liOOAslEiF7prFVr" Content-Disposition: inline In-Reply-To: <1240259085-25872-3-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rik van Riel , Hugh Dickins List-ID: --liOOAslEiF7prFVr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline A test program creates an anonymous memory mapping the size of the system's RAM (2G). It faults all pages of it linearly, then kicks off 128 reclaimers (on 4 cores) that map, fault and unmap 2G in sum and parallel, thereby evicting the first mapping onto swap. The time is then taken for the initial mapping to get faulted in from swap linearly again, thus measuring how bad the 128 reclaimers distributed the pages on the swap space. Average over 5 runs, standard deviation in parens: swap-in user system total old: 74.97s (0.38s) 0.52s (0.02s) 291.07s (3.28s) 2m52.66s (0m1.32s) new: 45.26s (0.68s) 0.53s (0.01s) 250.47s (5.17s) 2m45.93s (0m2.63s) where old is current mmotm snapshot 2009-04-17-15-19 and new is these three patches applied to it. Test program attached. Kernbench didn't show any differences on my single core x86 laptop with 256mb ram (poor thing). --liOOAslEiF7prFVr Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="contswap2.c" /* * contswap benchmark */ #include #include #include #include #include #include #include #define MEMORY (1650 << 20) #define RECLAIMERS 128 #define PAGE_SIZE 4096 #define PART (MEMORY / RECLAIMERS) static void *anonmap(unsigned long size) { void *map = mmap(NULL, size, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0); assert(map != MAP_FAILED); return map; } static void touch_linear(char *map, unsigned long size) { unsigned long off; for (off = 0; off < size; off += PAGE_SIZE) if (map[off]) puts("huh?"); } static void __claim(unsigned long size) { char *map = anonmap(size); touch_linear(map, size); sleep(5); munmap(map, size); } static pid_t claim(unsigned long size) { pid_t pid; switch (pid = fork()) { case -1: puts("fork failed"); exit(1); case 0: kill(getpid(), SIGSTOP); __claim(size); exit(0); default: return pid; } } int main(void) { struct timeval start, stop, diff; pid_t pids[RECLAIMERS]; int nr, crap; char *one; one = anonmap(MEMORY); touch_linear(one, MEMORY); for (nr = 0; nr < RECLAIMERS; nr++) pids[nr] = claim(PART); for (nr = 0; nr < RECLAIMERS; nr++) kill(pids[nr], SIGCONT); for (nr = 0; nr < RECLAIMERS; nr++) waitpid(pids[nr], &crap, 0); gettimeofday(&start, NULL); touch_linear(one, MEMORY); gettimeofday(&stop, NULL); munmap(one, MEMORY); timersub(&stop, &start, &diff); printf("%lu.%lu\n", diff.tv_sec, diff.tv_usec); return 0; } --liOOAslEiF7prFVr-- -- 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-mm.org/ . Don't email: email@kvack.org