LACOUNT: Add back lacount mechanism to defer migrating a fetched/read copy until...

This can improve performance slightly on certain workloads where smbds frequently read from the same record

diff --git a/client/ctdb_client.c b/client/ctdb_client.c
index 1b4143985fe66069b58931d733252a7ad0490ba5..9f4e8fd69d2ed4415b3b5f9a313a3fb9b2622316 100644 (file)
--- a/client/ctdb_client.c
+++ b/client/ctdb_client.c
@@ -71,7 +71,7 @@ struct ctdb_req_header *_ctdbd_allocate_pkt(struct ctdb_context *ctdb,
 */
 int ctdb_call_local(struct ctdb_db_context *ctdb_db, struct ctdb_call *call,
                    struct ctdb_ltdb_header *header, TALLOC_CTX *mem_ctx,
-                   TDB_DATA *data, bool updatetdb)
+                   TDB_DATA *data, bool updatetdb, uint32_t caller)
 {
        struct ctdb_call_info *c;
        struct ctdb_registered_call *fn;
@@ -106,7 +106,15 @@ int ctdb_call_local(struct ctdb_db_context *ctdb_db, struct ctdb_call *call,
        }
 
        /* we need to force the record to be written out if this was a remote access */
-       if (c->new_data == NULL) {
+       if (header->laccessor != caller) {
+               header->lacount = 0;
+       }
+       header->laccessor = caller;
+       header->lacount++;
+
+       /* we need to force the record to be written out if this was a remote access,
+          so that the lacount is updated */
+       if (c->new_data == NULL && header->laccessor != ctdb->pnn) {
                c->new_data = &c->record_data;
        }
 
@@ -386,7 +394,7 @@ static struct ctdb_client_call_state *ctdb_client_call_local_send(struct ctdb_db
        *(state->call) = *call;
        state->ctdb_db = ctdb_db;
 
-       ret = ctdb_call_local(ctdb_db, state->call, header, state, data, true);
+       ret = ctdb_call_local(ctdb_db, state->call, header, state, data, true, ctdb->pnn);
        if (ret != 0) {
                DEBUG(DEBUG_DEBUG,("ctdb_call_local() failed, ignoring return code %d\n", ret));
        }

diff --git a/common/ctdb_ltdb.c b/common/ctdb_ltdb.c
index 565a89986b88415a0031134d226e4c2585a5e3bf..3a184bb28c7cd12a4e0207b9d2d21cbed33b48c7 100644 (file)
--- a/common/ctdb_ltdb.c
+++ b/common/ctdb_ltdb.c
@@ -67,6 +67,7 @@ static void ltdb_initial_header(struct ctdb_db_context *ctdb_db,
        /* initial dmaster is the lmaster */
        header->dmaster = ctdb_lmaster(ctdb_db->ctdb, &key);
        header->flags = CTDB_REC_FLAG_AUTOMATIC;
+       header->laccessor = header->dmaster;
 }
 
 

diff --git a/include/ctdb_private.h b/include/ctdb_private.h
index aa687d4311bfa872b66752a8475886f65afa4978..3dff1c1bcc1c6e766e07f0e32dd96f9d66e79202 100644 (file)
--- a/include/ctdb_private.h
+++ b/include/ctdb_private.h
@@ -126,6 +126,7 @@ struct ctdb_tunable {
        uint32_t recover_pdb_by_seqnum;
        uint32_t deferred_rebalance_on_node_add;
        uint32_t fetch_collapse;
+       uint32_t max_lacount;
 };
 
 /*
@@ -798,7 +799,7 @@ struct ctdb_call_state *ctdb_daemon_call_send_remote(struct ctdb_db_context *ctd
 
 int ctdb_call_local(struct ctdb_db_context *ctdb_db, struct ctdb_call *call,
                    struct ctdb_ltdb_header *header, TALLOC_CTX *mem_ctx,
-                   TDB_DATA *data, bool updatetdb);
+                   TDB_DATA *data, bool updatetdb, uint32_t caller);
 
 #define ctdb_reqid_find(ctdb, reqid, type)     (type *)_ctdb_reqid_find(ctdb, reqid, #type, __location__)
 

diff --git a/include/ctdb_protocol.h b/include/ctdb_protocol.h
index ec52f5626c7b5db60a4e9d1571047ba78a6e95bc..8b113c3a0ed243c29789adf970a7aa1fc9410457 100644 (file)
--- a/include/ctdb_protocol.h
+++ b/include/ctdb_protocol.h
@@ -501,7 +501,8 @@ enum ctdb_trans2_commit_error {
 struct ctdb_ltdb_header {
        uint64_t rsn;
        uint32_t dmaster;
-       uint32_t reserved1;
+       uint16_t laccessor;
+       uint16_t lacount;
 #define CTDB_REC_FLAG_DEFAULT                  0x00000000
 #define CTDB_REC_FLAG_MIGRATED_WITH_DATA       0x00010000
 #define CTDB_REC_FLAG_VACUUM_MIGRATED          0x00020000

diff --git a/server/ctdb_call.c b/server/ctdb_call.c
index c015fbfff6684f7ed660a1717e17eb2575958006..dabfe5468f87fe949cfdecd1076f6a3c56c08537 100644 (file)
--- a/server/ctdb_call.c
+++ b/server/ctdb_call.c
@@ -338,7 +338,7 @@ static void ctdb_become_dmaster(struct ctdb_db_context *ctdb_db,
                return;
        }
 
-       ctdb_call_local(ctdb_db, state->call, &header, state, &data, true);
+       ctdb_call_local(ctdb_db, state->call, &header, state, &data, true, ctdb->pnn);
 
        ret = ctdb_ltdb_unlock(ctdb_db, state->call->key);
        if (ret != 0) {
@@ -643,11 +643,15 @@ void ctdb_request_call(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
        CTDB_INCREMENT_DB_STAT(ctdb_db, hop_count_bucket[bucket]);
 
 
-       /* Try if possible to migrate the record off to the caller node.
-        * From the clients perspective a fetch of the data is just as 
-        * expensive as a migration.
-        */
-       if (c->hdr.srcnode != ctdb->pnn) {
+       /* if this nodes has done enough consecutive calls on the same record
+          then give them the record
+          or if the node requested an immediate migration
+       */
+       if ( c->hdr.srcnode != ctdb->pnn &&
+            ((header.laccessor == c->hdr.srcnode
+              && header.lacount >= ctdb->tunable.max_lacount
+              && ctdb->tunable.max_lacount != 0)
+             || (c->flags & CTDB_IMMEDIATE_MIGRATION)) ) {
                if (ctdb_db->transaction_active) {
                        DEBUG(DEBUG_INFO, (__location__ " refusing migration"
                              " of key %s while transaction is active\n",
@@ -666,7 +670,7 @@ void ctdb_request_call(struct ctdb_context *ctdb, struct ctdb_req_header *hdr)
                }
        }
 
-       ret = ctdb_call_local(ctdb_db, call, &header, hdr, &data, true);
+       ret = ctdb_call_local(ctdb_db, call, &header, hdr, &data, true, c->hdr.srcnode);
        if (ret != 0) {
                DEBUG(DEBUG_ERR,(__location__ " ctdb_call_local failed\n"));
                call->status = -1;
@@ -953,7 +957,7 @@ struct ctdb_call_state *ctdb_call_local_send(struct ctdb_db_context *ctdb_db,
        *(state->call) = *call;
        state->ctdb_db = ctdb_db;
 
-       ret = ctdb_call_local(ctdb_db, state->call, header, state, data, true);
+       ret = ctdb_call_local(ctdb_db, state->call, header, state, data, true, ctdb->pnn);
        if (ret != 0) {
                DEBUG(DEBUG_DEBUG,("ctdb_call_local() failed, ignoring return code %d\n", ret));
        }

diff --git a/server/ctdb_tunables.c b/server/ctdb_tunables.c
index 016acc446717f82dc5c239bdca6684c332925de1..d09ac9bde9c7be28bd6d5bb2b6971c9038c47fda 100644 (file)
--- a/server/ctdb_tunables.c
+++ b/server/ctdb_tunables.c
@@ -74,7 +74,8 @@ static const struct {
        { "AllowClientDBAttach", 1, offsetof(struct ctdb_tunable, allow_client_db_attach), false },
        { "RecoverPDBBySeqNum",  0, offsetof(struct ctdb_tunable, recover_pdb_by_seqnum), false },
        { "DeferredRebalanceOnNodeAdd", 300, offsetof(struct ctdb_tunable, deferred_rebalance_on_node_add) },
-       { "FetchCollapse",       1, offsetof(struct ctdb_tunable, fetch_collapse) }
+       { "FetchCollapse",       1, offsetof(struct ctdb_tunable, fetch_collapse) },
+       { "MaxLACount",         20,  offsetof(struct ctdb_tunable, max_lacount) }
 };
 
 /*