replace nreserved with ndirty in txgs kstat

The nreserved column in the txgs kstat file always contains 0
following the write throttle restructuring of commit
e8b96c6007bf97cdf34869c1ffbd0ce753873a3d.

Prior to that commit, the nreserved column showed the number of bytes
temporarily reserved in the pool by a transaction group at sync time.
The new write throttle did away with temporary reservations and uses
the amount of dirty data instead.  To approximate the old output of
the txgs kstat, the number of dirty bytes per-txg was passed in as
the nreserved value to spa_txg_history_set_io().  This approach did
not work as intended, because the per-txg dirty value is decremented
as data is written out to disk, so it is zero by the time we call
spa_txg_history_set_io().  To fix this, save the number of dirty
bytes before calling spa_sync(), and pass this value in to
spa_txg_history_set_io().

Also, since the name "nreserved" is now a misnomer, the column
heading is now labeled "ndirty".

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #1696

diff --git a/include/sys/spa.h b/include/sys/spa.h
index e7cbff806d983fe6d37995080309d3ba16ca1986..d5a91c2d31f9aa7f4a5993c260ddd35a2816d22a 100644 (file)
--- a/include/sys/spa.h
+++ b/include/sys/spa.h
@@ -570,7 +570,7 @@ extern void spa_txg_history_add(spa_t *spa, uint64_t txg, hrtime_t birth_time);
 extern int spa_txg_history_set(spa_t *spa,  uint64_t txg,
     txg_state_t completed_state, hrtime_t completed_time);
 extern int spa_txg_history_set_io(spa_t *spa,  uint64_t txg, uint64_t nread,
-    uint64_t nwritten, uint64_t reads, uint64_t writes, uint64_t nreserved);
+    uint64_t nwritten, uint64_t reads, uint64_t writes, uint64_t ndirty);
 extern void spa_tx_assign_add_nsecs(spa_t *spa, uint64_t nsecs);
 
 /* Pool configuration locks */

diff --git a/module/zfs/spa_stats.c b/module/zfs/spa_stats.c
index a35f5df6560982a716adc46341568ad0a26f8225..dbc761e115d5a7fea577011600ad6a119244a790 100644 (file)
--- a/module/zfs/spa_stats.c
+++ b/module/zfs/spa_stats.c
@@ -248,7 +248,7 @@ typedef struct spa_txg_history {
        uint64_t        nwritten;       /* number of bytes written */
        uint64_t        reads;          /* number of read operations */
        uint64_t        writes;         /* number of write operations */
-       uint64_t        nreserved;      /* number of bytes reserved */
+       uint64_t        ndirty;         /* number of dirty bytes */
        hrtime_t        times[TXG_STATE_COMMITTED]; /* completion times */
        list_node_t     sth_link;
 } spa_txg_history_t;
@@ -258,7 +258,7 @@ spa_txg_history_headers(char *buf, size_t size)
 {
        size = snprintf(buf, size - 1, "%-8s %-16s %-5s %-12s %-12s %-12s "
            "%-8s %-8s %-12s %-12s %-12s %-12s\n", "txg", "birth", "state",
-           "nreserved", "nread", "nwritten", "reads", "writes",
+           "ndirty", "nread", "nwritten", "reads", "writes",
            "otime", "qtime", "wtime", "stime");
        buf[size] = '\0';
 
@@ -301,7 +301,7 @@ spa_txg_history_data(char *buf, size_t size, void *data)
        size = snprintf(buf, size - 1, "%-8llu %-16llu %-5c %-12llu "
            "%-12llu %-12llu %-8llu %-8llu %-12llu %-12llu %-12llu %-12llu\n",
            (longlong_t)sth->txg, sth->times[TXG_STATE_BIRTH], state,
-           (u_longlong_t)sth->nreserved,
+           (u_longlong_t)sth->ndirty,
            (u_longlong_t)sth->nread, (u_longlong_t)sth->nwritten,
            (u_longlong_t)sth->reads, (u_longlong_t)sth->writes,
            (u_longlong_t)open, (u_longlong_t)quiesce, (u_longlong_t)wait,
@@ -482,7 +482,7 @@ spa_txg_history_set(spa_t *spa, uint64_t txg, txg_state_t completed_state,
  */
 int
 spa_txg_history_set_io(spa_t *spa, uint64_t txg, uint64_t nread,
-    uint64_t nwritten, uint64_t reads, uint64_t writes, uint64_t nreserved)
+    uint64_t nwritten, uint64_t reads, uint64_t writes, uint64_t ndirty)
 {
        spa_stats_history_t *ssh = &spa->spa_stats.txg_history;
        spa_txg_history_t *sth;
@@ -499,7 +499,7 @@ spa_txg_history_set_io(spa_t *spa, uint64_t txg, uint64_t nread,
                        sth->nwritten = nwritten;
                        sth->reads = reads;
                        sth->writes = writes;
-                       sth->nreserved = nreserved;
+                       sth->ndirty = ndirty;
                        error = 0;
                        break;
                }

diff --git a/module/zfs/txg.c b/module/zfs/txg.c
index 9e9db9989fb791e0376832e398291417b803cc67..524fe8e84367947471c10899c452dc4284084420 100644 (file)
--- a/module/zfs/txg.c
+++ b/module/zfs/txg.c
@@ -500,6 +500,7 @@ txg_sync_thread(dsl_pool_t *dp)
        for (;;) {
                uint64_t timer, timeout;
                uint64_t txg;
+               uint64_t ndirty;
 
                timeout = zfs_txg_timeout * hz;
 
@@ -557,6 +558,7 @@ txg_sync_thread(dsl_pool_t *dp)
 
                spa_txg_history_set(spa, txg, TXG_STATE_WAIT_FOR_SYNC,
                    gethrtime());
+               ndirty = dp->dp_dirty_pertxg[txg & TXG_MASK];
 
                start = ddi_get_lbolt();
                spa_sync(spa, txg);
@@ -579,7 +581,7 @@ txg_sync_thread(dsl_pool_t *dp)
                    vs2->vs_bytes[ZIO_TYPE_WRITE]-vs1->vs_bytes[ZIO_TYPE_WRITE],
                    vs2->vs_ops[ZIO_TYPE_READ]-vs1->vs_ops[ZIO_TYPE_READ],
                    vs2->vs_ops[ZIO_TYPE_WRITE]-vs1->vs_ops[ZIO_TYPE_WRITE],
-                   dp->dp_dirty_pertxg[txg & TXG_MASK]);
+                   ndirty);
                spa_txg_history_set(spa, txg, TXG_STATE_SYNCED, gethrtime());
        }
 }