From 087efdd391f47305dc251a7b00dcc5d69e8c636a Mon Sep 17 00:00:00 2001 From: Steven Whitehouse Date: Sat, 9 Sep 2006 16:59:11 -0400 Subject: [PATCH] [GFS2] Make glock hash locks proportional to NR_CPUS Make the number of locks used for hash chains in glock.c proportional to NR_CPUS. Also move constants for the number of hash chains into glock.c from incore.h since they are not used outside of glock.c. Signed-off-by: Steven Whitehouse --- fs/gfs2/glock.c | 93 ++++++++++++++++++++++++++++++++++++++---------- fs/gfs2/incore.h | 3 -- 2 files changed, 74 insertions(+), 22 deletions(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 49512696160e..8abfefe4efd4 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -53,8 +53,59 @@ typedef void (*glock_examiner) (struct gfs2_glock * gl); static int gfs2_dump_lockstate(struct gfs2_sbd *sdp); static int dump_glock(struct gfs2_glock *gl); +#define GFS2_GL_HASH_SHIFT 13 +#define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT) +#define GFS2_GL_HASH_MASK (GFS2_GL_HASH_SIZE - 1) + static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE]; -static rwlock_t gl_hash_locks[GFS2_GL_HASH_SIZE]; + +/* + * Despite what you might think, the numbers below are not arbitrary :-) + * They are taken from the ipv4 routing hash code, which is well tested + * and thus should be nearly optimal. Later on we might tweek the numbers + * but for now this should be fine. + * + * The reason for putting the locks in a separate array from the list heads + * is that we can have fewer locks than list heads and save memory. We use + * the same hash function for both, but with a different hash mask. + */ +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \ + defined(CONFIG_PROVE_LOCKING) + +#ifdef CONFIG_LOCKDEP +# define GL_HASH_LOCK_SZ 256 +#else +# if NR_CPUS >= 32 +# define GL_HASH_LOCK_SZ 4096 +# elif NR_CPUS >= 16 +# define GL_HASH_LOCK_SZ 2048 +# elif NR_CPUS >= 8 +# define GL_HASH_LOCK_SZ 1024 +# elif NR_CPUS >= 4 +# define GL_HASH_LOCK_SZ 512 +# else +# define GL_HASH_LOCK_SZ 256 +# endif +#endif + +/* We never want more locks than chains */ +#if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ +# undef GL_HASH_LOCK_SZ +# define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE +#endif + +static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ]; + +static inline rwlock_t *gl_lock_addr(unsigned int x) +{ + return &gl_hash_locks[(x) & (GL_HASH_LOCK_SZ-1)]; +} +#else /* not SMP, so no spinlocks required */ +static inline rwlock_t *gl_lock_addr(x) +{ + return NULL; +} +#endif /** * relaxed_state_ok - is a requested lock compatible with the current lock mode? @@ -161,16 +212,16 @@ int gfs2_glock_put(struct gfs2_glock *gl) { int rv = 0; - write_lock(&gl_hash_locks[gl->gl_hash]); + write_lock(gl_lock_addr(gl->gl_hash)); if (kref_put(&gl->gl_ref, kill_glock)) { list_del_init(&gl_hash_table[gl->gl_hash].hb_list); - write_unlock(&gl_hash_locks[gl->gl_hash]); + write_unlock(gl_lock_addr(gl->gl_hash)); BUG_ON(spin_is_locked(&gl->gl_spin)); glock_free(gl); rv = 1; goto out; } - write_unlock(&gl_hash_locks[gl->gl_hash]); + write_unlock(gl_lock_addr(gl->gl_hash)); out: return rv; } @@ -243,9 +294,9 @@ static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp, unsigned int hash = gl_hash(sdp, name); struct gfs2_glock *gl; - read_lock(&gl_hash_locks[hash]); + read_lock(gl_lock_addr(hash)); gl = search_bucket(hash, sdp, name); - read_unlock(&gl_hash_locks[hash]); + read_unlock(gl_lock_addr(hash)); return gl; } @@ -272,9 +323,9 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, unsigned int hash = gl_hash(sdp, &name); int error; - read_lock(&gl_hash_locks[hash]); + read_lock(gl_lock_addr(hash)); gl = search_bucket(hash, sdp, &name); - read_unlock(&gl_hash_locks[hash]); + read_unlock(gl_lock_addr(hash)); if (gl || !create) { *glp = gl; @@ -316,15 +367,15 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number, if (error) goto fail_aspace; - write_lock(&gl_hash_locks[hash]); + write_lock(gl_lock_addr(hash)); tmp = search_bucket(hash, sdp, &name); if (tmp) { - write_unlock(&gl_hash_locks[hash]); + write_unlock(gl_lock_addr(hash)); glock_free(gl); gl = tmp; } else { list_add_tail(&gl->gl_list, &gl_hash_table[hash].hb_list); - write_unlock(&gl_hash_locks[hash]); + write_unlock(gl_lock_addr(hash)); } *glp = gl; @@ -1879,12 +1930,12 @@ static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp, memset(&plug.gl_flags, 0, sizeof(unsigned long)); set_bit(GLF_PLUG, &plug.gl_flags); - write_lock(&gl_hash_locks[hash]); + write_lock(gl_lock_addr(hash)); list_add(&plug.gl_list, &gl_hash_table[hash].hb_list); - write_unlock(&gl_hash_locks[hash]); + write_unlock(gl_lock_addr(hash)); for (;;) { - write_lock(&gl_hash_locks[hash]); + write_lock(gl_lock_addr(hash)); for (;;) { tmp = plug.gl_list.next; @@ -1892,7 +1943,7 @@ static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp, if (tmp == &gl_hash_table[hash].hb_list) { list_del(&plug.gl_list); entries = !list_empty(&gl_hash_table[hash].hb_list); - write_unlock(&gl_hash_locks[hash]); + write_unlock(gl_lock_addr(hash)); return entries; } gl = list_entry(tmp, struct gfs2_glock, gl_list); @@ -1911,7 +1962,7 @@ static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp, break; } - write_unlock(&gl_hash_locks[hash]); + write_unlock(gl_lock_addr(hash)); examiner(gl); } @@ -2204,7 +2255,7 @@ static int gfs2_dump_lockstate(struct gfs2_sbd *sdp) for (x = 0; x < GFS2_GL_HASH_SIZE; x++) { - read_lock(&gl_hash_locks[x]); + read_lock(gl_lock_addr(x)); list_for_each_entry(gl, &gl_hash_table[x].hb_list, gl_list) { if (test_bit(GLF_PLUG, &gl->gl_flags)) @@ -2217,7 +2268,7 @@ static int gfs2_dump_lockstate(struct gfs2_sbd *sdp) break; } - read_unlock(&gl_hash_locks[x]); + read_unlock(gl_lock_addr(x)); if (error) break; @@ -2231,9 +2282,13 @@ int __init gfs2_glock_init(void) { unsigned i; for(i = 0; i < GFS2_GL_HASH_SIZE; i++) { - rwlock_init(&gl_hash_locks[i]); INIT_LIST_HEAD(&gl_hash_table[i].hb_list); } +#ifdef GL_HASH_LOCK_SZ + for(i = 0; i < GL_HASH_LOCK_SZ; i++) { + rwlock_init(&gl_hash_locks[i]); + } +#endif return 0; } diff --git a/fs/gfs2/incore.h b/fs/gfs2/incore.h index f50ea6282e77..64e13435ca3b 100644 --- a/fs/gfs2/incore.h +++ b/fs/gfs2/incore.h @@ -448,9 +448,6 @@ enum { SDF_NOATIME = 3, }; -#define GFS2_GL_HASH_SHIFT 13 -#define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT) -#define GFS2_GL_HASH_MASK (GFS2_GL_HASH_SIZE - 1) #define GFS2_FSNAME_LEN 256 struct gfs2_sbd {