From b6ad9671acdd245385744bcc1fe6c0f21f252570 Mon Sep 17 00:00:00 2001 From: Etienne Dechamps Date: Fri, 15 Jun 2012 16:22:14 +0200 Subject: Add ZIL statistics. The performance of the ZIL is usually the main bottleneck when dealing with synchronous, write-heavy workloads (e.g. databases). Understanding the behavior of the ZIL is required to diagnose performance issues for these workloads, and to tune ZIL parameters (like zil_slog_limit) accordingly. This commit adds a new kstat page dedicated to the ZIL with some counters which, hopefully, scheds some light into what the ZIL is doing, and how it is doing it. Currently, these statistics are available in /proc/spl/kstat/zfs/zil. A description of the fields can be found in zil.h. Signed-off-by: Brian Behlendorf Closes #786 --- module/zfs/zil.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 61 insertions(+), 2 deletions(-) (limited to 'module') diff --git a/module/zfs/zil.c b/module/zfs/zil.c index fb0503628..9ab02d70c 100644 --- a/module/zfs/zil.c +++ b/module/zfs/zil.c @@ -65,6 +65,27 @@ * needed from the blocks available. Figure X shows the ZIL structure: */ +/* + * See zil.h for more information about these fields. + */ +zil_stats_t zil_stats = { + { "zil_commit_count", KSTAT_DATA_UINT64 }, + { "zil_commit_writer_count", KSTAT_DATA_UINT64 }, + { "zil_itx_count", KSTAT_DATA_UINT64 }, + { "zil_itx_indirect_count", KSTAT_DATA_UINT64 }, + { "zil_itx_indirect_bytes", KSTAT_DATA_UINT64 }, + { "zil_itx_copied_count", KSTAT_DATA_UINT64 }, + { "zil_itx_copied_bytes", KSTAT_DATA_UINT64 }, + { "zil_itx_needcopy_count", KSTAT_DATA_UINT64 }, + { "zil_itx_needcopy_bytes", KSTAT_DATA_UINT64 }, + { "zil_itx_metaslab_normal_count", KSTAT_DATA_UINT64 }, + { "zil_itx_metaslab_normal_bytes", KSTAT_DATA_UINT64 }, + { "zil_itx_metaslab_slog_count", KSTAT_DATA_UINT64 }, + { "zil_itx_metaslab_slog_bytes", KSTAT_DATA_UINT64 }, +}; + +static kstat_t *zil_ksp; + /* * This global ZIL switch affects all pools */ @@ -879,6 +900,7 @@ zil_lwb_write_start(zilog_t *zilog, lwb_t *lwb) uint64_t txg; uint64_t zil_blksz, wsz; int i, error; + boolean_t use_slog; if (BP_GET_CHECKSUM(&lwb->lwb_blk) == ZIO_CHECKSUM_ZILOG2) { zilc = (zil_chain_t *)lwb->lwb_buf; @@ -935,8 +957,19 @@ zil_lwb_write_start(zilog_t *zilog, lwb_t *lwb) BP_ZERO(bp); /* pass the old blkptr in order to spread log blocks across devs */ + use_slog = USE_SLOG(zilog); error = zio_alloc_zil(spa, txg, bp, &lwb->lwb_blk, zil_blksz, - USE_SLOG(zilog)); + use_slog); + if (use_slog) + { + ZIL_STAT_BUMP(zil_itx_metaslab_slog_count); + ZIL_STAT_INCR(zil_itx_metaslab_slog_bytes, lwb->lwb_nused); + } + else + { + ZIL_STAT_BUMP(zil_itx_metaslab_normal_count); + ZIL_STAT_INCR(zil_itx_metaslab_normal_bytes, lwb->lwb_nused); + } if (!error) { ASSERT3U(bp->blk_birth, ==, txg); bp->blk_cksum = lwb->lwb_blk.blk_cksum; @@ -1022,13 +1055,18 @@ zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb) lrc = (lr_t *)lr_buf; lrw = (lr_write_t *)lrc; + ZIL_STAT_BUMP(zil_itx_count); + /* * If it's a write, fetch the data or get its blkptr as appropriate. */ if (lrc->lrc_txtype == TX_WRITE) { if (txg > spa_freeze_txg(zilog->zl_spa)) txg_wait_synced(zilog->zl_dmu_pool, txg); - if (itx->itx_wr_state != WR_COPIED) { + if (itx->itx_wr_state == WR_COPIED) { + ZIL_STAT_BUMP(zil_itx_copied_count); + ZIL_STAT_INCR(zil_itx_copied_bytes, lrw->lr_length); + } else { char *dbuf; int error; @@ -1036,9 +1074,13 @@ zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb) ASSERT(itx->itx_wr_state == WR_NEED_COPY); dbuf = lr_buf + reclen; lrw->lr_common.lrc_reclen += dlen; + ZIL_STAT_BUMP(zil_itx_needcopy_count); + ZIL_STAT_INCR(zil_itx_needcopy_bytes, lrw->lr_length); } else { ASSERT(itx->itx_wr_state == WR_INDIRECT); dbuf = NULL; + ZIL_STAT_BUMP(zil_itx_indirect_count); + ZIL_STAT_INCR(zil_itx_indirect_bytes, lrw->lr_length); } error = zilog->zl_get_data( itx->itx_private, lrw, dbuf, lwb->lwb_zio); @@ -1497,6 +1539,8 @@ zil_commit(zilog_t *zilog, uint64_t foid) if (zilog->zl_sync == ZFS_SYNC_DISABLED) return; + ZIL_STAT_BUMP(zil_commit_count); + /* move the async itxs for the foid to the sync queues */ zil_async_to_sync(zilog, foid); @@ -1512,6 +1556,7 @@ zil_commit(zilog_t *zilog, uint64_t foid) zilog->zl_next_batch++; zilog->zl_writer = B_TRUE; + ZIL_STAT_BUMP(zil_commit_writer_count); zil_commit_writer(zilog); zilog->zl_com_batch = mybatch; zilog->zl_writer = B_FALSE; @@ -1600,12 +1645,26 @@ zil_init(void) { zil_lwb_cache = kmem_cache_create("zil_lwb_cache", sizeof (struct lwb), 0, NULL, NULL, NULL, NULL, NULL, 0); + + zil_ksp = kstat_create("zfs", 0, "zil", "misc", + KSTAT_TYPE_NAMED, sizeof(zil_stats) / sizeof(kstat_named_t), + KSTAT_FLAG_VIRTUAL); + + if (zil_ksp != NULL) { + zil_ksp->ks_data = &zil_stats; + kstat_install(zil_ksp); + } } void zil_fini(void) { kmem_cache_destroy(zil_lwb_cache); + + if (zil_ksp != NULL) { + kstat_delete(zil_ksp); + zil_ksp = NULL; + } } void -- cgit v1.2.3