From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [uPatch] Re: Graceful failure? References: From: "John Fremlin" Date: 05 Jun 2000 21:21:25 +0100 In-Reply-To: Rik van Riel's message of "Mon, 5 Jun 2000 13:03:08 -0300 (BRST)" Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Billy Harvey , Linux Kernel , linux-mm@kvack.org List-ID: Rik van Riel writes: > On Mon, 5 Jun 2000, Billy Harvey wrote: > > > A "make -j" slowly over the course of 5 minutes drives the load > > to about 30. At first the degradation is controlled, with > > sendmail refusing service, but at about 160 process visible in > > top, top quits updating (set a 8 second updates), showing about > > 2 MB swap used. At this point it sounds like the system is > > thrashing. > > That probably means you're a lot more in swap now and top > has stopped displaying before you really hit the swap... Allow me to hype my patch again. Could someone please test it? It improves performance markedly (no horrible pauses in vmscan.c:swap_out under heavy load). > > > Is this failure process acceptable? I'd think the system should > > react differently to the thrashing, killing off the load > > demanding user process(es), rather than degrading to a point of > > freeze. My patch fixes this for me, please test. [...] --- linux-2.4.0t1a7m3/mm/vmscan.c Sat Jun 3 17:10:15 2000 +++ kernel-hacking/mm/vmscan.c Sun Jun 4 16:35:31 2000 @@ -361,23 +361,24 @@ /* * We make one or two passes through the task list, indexed by * assign = {0, 1}: - * Pass 1: select the swappable task with maximal RSS that has - * not yet been swapped out. + * + * Pass 1: select the first swappable task that has not yet + * been swapped out. + * * Pass 2: re-assign rss swap_cnt values, then select as above. * * With this approach, there's no need to remember the last task * swapped out. If the swap-out fails, we clear swap_cnt so the * task won't be selected again until all others have been tried. * - * Think of swap_cnt as a "shadow rss" - it tells us which process - * we want to page out (always try largest first). - */ + * Think of swap_cnt as a "shadow rss" - it tells us which + * process we want to page out (always try largest first). */ + counter = (nr_threads << 2) >> (priority >> 2); if (counter < 1) counter = 1; for (; counter >= 0; counter--) { - unsigned long max_cnt = 0; struct mm_struct *best = NULL; int pid = 0; int assign = 0; @@ -391,13 +392,14 @@ if (mm->rss <= 0) continue; /* Refresh swap_cnt? */ - if (assign == 1) + best = mm; + pid = p->pid; + + if (assign == 1){ mm->swap_cnt = mm->rss; - if (mm->swap_cnt > max_cnt) { - max_cnt = mm->swap_cnt; - best = mm; - pid = p->pid; } + else + break; } read_unlock(&tasklist_lock); if (!best) { -- http://altern.org/vii -- 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/