From 43518d92fd9200aa07a871604a682e0dc7dff981 Mon Sep 17 00:00:00 2001 From: tuxoko Date: Fri, 30 Oct 2015 16:10:01 -0700 Subject: [PATCH] Fix zfs_dirty_data_max overflow on 32-bit On 32 bit, the calculation of zfs_dirty_data_max from phymem will overflow, causing it to be smaller than zfs_dirty_data_sync, and will cause txg being delayed while no one write to disk. The end result is horrendous write speed. On 4G ram 32-bit VM, before this patch, simple dd results in ~7MB/s. Now it can reach speed on par with 64-bit VM. Signed-off-by: Chunwei Chen Signed-off-by: Brian Behlendorf Closes #3973 --- module/zfs/arc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/module/zfs/arc.c b/module/zfs/arc.c index c1e0bfbba..4e7e05924 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -5479,11 +5479,11 @@ arc_init(void) * zfs_dirty_data_max_max (default 25% of physical memory). */ if (zfs_dirty_data_max_max == 0) - zfs_dirty_data_max_max = physmem * PAGESIZE * + zfs_dirty_data_max_max = (uint64_t)physmem * PAGESIZE * zfs_dirty_data_max_max_percent / 100; if (zfs_dirty_data_max == 0) { - zfs_dirty_data_max = physmem * PAGESIZE * + zfs_dirty_data_max = (uint64_t)physmem * PAGESIZE * zfs_dirty_data_max_percent / 100; zfs_dirty_data_max = MIN(zfs_dirty_data_max, zfs_dirty_data_max_max);