From b07f8f24dfe54da0f074b78949044842e8df881f Mon Sep 17 00:00:00 2001 From: Mark Fasheh Date: Mon, 5 Apr 2010 18:17:15 -0700 Subject: [PATCH] ocfs2: change default reservation window sizes The default reservation size of 4 (32-bit windows) is a bit too ambitious. Scale it back to 16 bits (resv_level=2). I have been testing various sizes on a 4-node cluster which runs a mixed workload that is heavily threaded. With a 256MB local alloc, I get *roughly* the following levels of average file fragmentation: resv_level=0 70% resv_level=1 21% resv_level=2 23% resv_level=3 24% resv_level=4 60% resv_level=5 did not test resv_level=6 60% resv_level=2 seemed like a good compromise between not letting windows be too small, but not so big that heavier workloads will immediately suffer without tuning. This patch also change the behavior of directory reservations - they now track file reservations. The previous compromise of giving directory windows only 8 bits wound up fragmenting more at some window sizes because file allocations had smaller unused windows to poach from. Signed-off-by: Mark Fasheh Signed-off-by: Joel Becker --- Documentation/filesystems/ocfs2.txt | 2 +- fs/ocfs2/reservations.c | 7 ++++--- fs/ocfs2/reservations.h | 2 +- 3 files changed, 6 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt index 412df90..32339e5 100644 --- a/Documentation/filesystems/ocfs2.txt +++ b/Documentation/filesystems/ocfs2.txt @@ -80,6 +80,6 @@ user_xattr (*) Enables Extended User Attributes. nouser_xattr Disables Extended User Attributes. acl Enables POSIX Access Control Lists support. noacl (*) Disables POSIX Access Control Lists support. -resv_level=4 (*) Set how agressive allocation reservations will be. +resv_level=2 (*) Set how agressive allocation reservations will be. Valid values are between 0 (reservations off) to 8 (maximum space for reservations). diff --git a/fs/ocfs2/reservations.c b/fs/ocfs2/reservations.c index 7fc6cfe..87fa357 100644 --- a/fs/ocfs2/reservations.c +++ b/fs/ocfs2/reservations.c @@ -55,9 +55,10 @@ static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap, if (!(resv->r_flags & OCFS2_RESV_FLAG_DIR)) { /* 8, 16, 32, 64, 128, 256, 512, 1024 */ bits = 4 << osb->osb_resv_level; - } else - bits = OCFS2_RESV_DIR_WINDOW_BITS; - + } else { + /* For now, treat directories the same as files. */ + bits = 4 << osb->osb_resv_level; + } return bits; } diff --git a/fs/ocfs2/reservations.h b/fs/ocfs2/reservations.h index 34bb308..022aff6 100644 --- a/fs/ocfs2/reservations.h +++ b/fs/ocfs2/reservations.h @@ -22,7 +22,7 @@ #include -#define OCFS2_DEFAULT_RESV_LEVEL 4 +#define OCFS2_DEFAULT_RESV_LEVEL 2 #define OCFS2_MAX_RESV_LEVEL 9 #define OCFS2_MIN_RESV_LEVEL 0 -- 2.7.4