Messages in this thread | | | Date | Thu, 16 Oct 2003 15:33:04 +0200 | From | Andrea Arcangeli <> | Subject | Re: Strange dcache memory pressure when highmem enabled |
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On Tue, Oct 14, 2003 at 10:43:52PM -0700, Andrew Morton wrote: > Neil Brown <neilb@cse.unsw.edu.au> wrote: > > > > I noticed that shrink_caches calls shrink_dcache_memory independant > > of the classzone that is being shrunk. So if we are trying to > > shrink ZONE_HIGHMEM, the dentry_cache is shrunk, even though the > > dentry_cache doesn't live in highmem. However I'm not sure if I have > > understood the classzones well enough for that observation even to > > make sense. > > Makes heaps of sense. Here's an instabackport of what we did in 2.6: > > mm/vmscan.c | 12 +++++++++--- > 1 files changed, 9 insertions(+), 3 deletions(-) > > diff -puN mm/vmscan.c~a mm/vmscan.c > --- 24/mm/vmscan.c~a 2003-10-14 22:41:34.000000000 -0700 > +++ 24-akpm/mm/vmscan.c 2003-10-14 22:42:22.000000000 -0700 > @@ -640,11 +640,17 @@ int try_to_free_pages_zone(zone_t *class > nr_pages = shrink_caches(classzone, gfp_mask, nr_pages, &failed_swapout); > if (nr_pages <= 0) > return 1; > - shrink_dcache_memory(vm_vfs_scan_ratio, gfp_mask); > - shrink_icache_memory(vm_vfs_scan_ratio, gfp_mask); > + if (classzone - classzone->zone_pgdat->node_zones < > + ZONE_HIGHMEM) { > + shrink_dcache_memory(vm_vfs_scan_ratio, > + gfp_mask); > + shrink_icache_memory(vm_vfs_scan_ratio, > + gfp_mask); > #ifdef CONFIG_QUOTA > - shrink_dqcache_memory(vm_vfs_scan_ratio, gfp_mask); > + shrink_dqcache_memory(vm_vfs_scan_ratio, > + gfp_mask); > #endif > + } > if (!failed_swapout) > failed_swapout = !swap_out(classzone); > } while (--tries);
An highmem user can make use of lowmem too. Think a 1G box, it looks wrong to disallow highmem to shrink the 800M of dcache in the normal/dma zones.
I wonder if what he's suffering from is a reduced normal zone due the mem_map_t being larger. The reduced normal zone will trigger the dcache shrinking more frequently. But he may want to try again with 2.4.23pre7 with a classzone aware refill_inactive that will ensure the inactive list has enough lowmem pages before shrink_caches claims failure.
Andrea - If you prefer relying on open source software, check these links: rsync.kernel.org::pub/scm/linux/kernel/bkcvs/linux-2.[45]/ http://www.cobite.com/cvsps/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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