git: 812c9f48a2b7 - main - Save context switch per I/O for iSCSI and IOCTL frontends.
Alexander Motin
mav at FreeBSD.org
Fri Feb 19 03:29:42 UTC 2021
The branch main has been updated by mav:
URL: https://cgit.FreeBSD.org/src/commit/?id=812c9f48a2b7bccc31b2a6077b299822357832e4
commit 812c9f48a2b7bccc31b2a6077b299822357832e4
Author: Alexander Motin <mav at FreeBSD.org>
AuthorDate: 2021-02-19 03:07:32 +0000
Commit: Alexander Motin <mav at FreeBSD.org>
CommitDate: 2021-02-19 03:29:38 +0000
Save context switch per I/O for iSCSI and IOCTL frontends.
Introduce new CTL core KPI ctl_run(), preprocessing I/Os in the caller
context instead of scheduling another thread just for that. This call
may sleep, that is not acceptable for some frontends like the original
CAM/FC one, but iSCSI already has separate sleepable per-connection RX
threads, and another thread scheduling is mostly just a waste of time.
IOCTL frontend actually waits for the I/O completion in the caller
thread, so the use of another thread for this has even less sense.
With this change I can measure ~5% IOPS improvement on 4KB iSCSI I/Os
to ZFS.
MFC after: 1 month
---
sys/cam/ctl/README.ctl.txt | 2 +-
sys/cam/ctl/ctl.c | 65 ++++++++++++++++++++++++++++++----------
sys/cam/ctl/ctl_frontend.h | 7 +++++
sys/cam/ctl/ctl_frontend_ioctl.c | 2 +-
sys/cam/ctl/ctl_frontend_iscsi.c | 12 ++++----
sys/cam/ctl/ctl_tpc.c | 2 +-
6 files changed, 65 insertions(+), 25 deletions(-)
diff --git a/sys/cam/ctl/README.ctl.txt b/sys/cam/ctl/README.ctl.txt
index 27ebe49aec56..db8666ea99db 100644
--- a/sys/cam/ctl/README.ctl.txt
+++ b/sys/cam/ctl/README.ctl.txt
@@ -258,7 +258,7 @@ point.
Here is a roadmap of some of the primary functions in ctl.c. Starting here
and following the various leaf functions will show the command flow.
-ctl_queue() This is where commands from the frontend ports come
+ctl_queue() / ctl_run() This is where commands from the frontend ports come
in.
ctl_queue_sense() This is only used for non-packetized SCSI. i.e.
diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
index 37962eb3522c..d7769e270016 100644
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -513,8 +513,7 @@ static int ctl_scsiio_lun_check(struct ctl_lun *lun,
const struct ctl_cmd_entry *entry,
struct ctl_scsiio *ctsio);
static void ctl_failover_lun(union ctl_io *io);
-static int ctl_scsiio_precheck(struct ctl_softc *ctl_softc,
- struct ctl_scsiio *ctsio);
+static void ctl_scsiio_precheck(struct ctl_scsiio *ctsio);
static int ctl_scsiio(struct ctl_scsiio *ctsio);
static int ctl_target_reset(union ctl_io *io);
@@ -11437,14 +11436,14 @@ ctl_failover_lun(union ctl_io *rio)
mtx_unlock(&lun->lun_lock);
}
-static int
-ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
+static void
+ctl_scsiio_precheck(struct ctl_scsiio *ctsio)
{
+ struct ctl_softc *softc = CTL_SOFTC(ctsio);
struct ctl_lun *lun;
const struct ctl_cmd_entry *entry;
union ctl_io *bio;
uint32_t initidx, targ_lun;
- int retval = 0;
lun = NULL;
targ_lun = ctsio->io_hdr.nexus.targ_mapped_lun;
@@ -11482,7 +11481,7 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
if (entry == NULL) {
if (lun)
mtx_unlock(&lun->lun_lock);
- return (retval);
+ return;
}
ctsio->io_hdr.flags &= ~CTL_FLAG_DATA_MASK;
@@ -11499,13 +11498,13 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
if (entry->flags & CTL_CMD_FLAG_OK_ON_NO_LUN) {
ctsio->io_hdr.flags |= CTL_FLAG_IS_WAS_ON_RTR;
ctl_enqueue_rtr((union ctl_io *)ctsio);
- return (retval);
+ return;
}
ctl_set_unsupported_lun(ctsio);
ctl_done((union ctl_io *)ctsio);
CTL_DEBUG_PRINT(("ctl_scsiio_precheck: bailing out due to invalid LUN\n"));
- return (retval);
+ return;
} else {
/*
* Make sure we support this particular command on this LUN.
@@ -11515,7 +11514,7 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
mtx_unlock(&lun->lun_lock);
ctl_set_invalid_opcode(ctsio);
ctl_done((union ctl_io *)ctsio);
- return (retval);
+ return;
}
}
@@ -11569,14 +11568,14 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
ctsio->io_hdr.status = CTL_SCSI_ERROR | CTL_AUTOSENSE;
ctsio->sense_len = sense_len;
ctl_done((union ctl_io *)ctsio);
- return (retval);
+ return;
}
}
if (ctl_scsiio_lun_check(lun, entry, ctsio) != 0) {
mtx_unlock(&lun->lun_lock);
ctl_done((union ctl_io *)ctsio);
- return (retval);
+ return;
}
/*
@@ -11613,9 +11612,9 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
M_WAITOK)) > CTL_HA_STATUS_SUCCESS) {
ctl_set_busy(ctsio);
ctl_done((union ctl_io *)ctsio);
- return (retval);
+ return;
}
- return (retval);
+ return;
}
bio = (union ctl_io *)TAILQ_PREV(&ctsio->io_hdr, ctl_ooaq, ooa_links);
@@ -11625,7 +11624,7 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
TAILQ_INSERT_TAIL(&bio->io_hdr.blocked_queue, &ctsio->io_hdr,
blocked_links);
mtx_unlock(&lun->lun_lock);
- return (retval);
+ break;
case CTL_ACTION_PASS:
case CTL_ACTION_SKIP:
ctsio->io_hdr.flags |= CTL_FLAG_IS_WAS_ON_RTR;
@@ -11651,7 +11650,6 @@ ctl_scsiio_precheck(struct ctl_softc *softc, struct ctl_scsiio *ctsio)
ctl_done((union ctl_io *)ctsio);
break;
}
- return (retval);
}
const struct ctl_cmd_entry *
@@ -13253,6 +13251,41 @@ ctl_queue(union ctl_io *io)
return (CTL_RETVAL_COMPLETE);
}
+int
+ctl_run(union ctl_io *io)
+{
+ struct ctl_port *port = CTL_PORT(io);
+
+ CTL_DEBUG_PRINT(("ctl_run cdb[0]=%02X\n", io->scsiio.cdb[0]));
+
+#ifdef CTL_TIME_IO
+ io->io_hdr.start_time = time_uptime;
+ getbinuptime(&io->io_hdr.start_bt);
+#endif /* CTL_TIME_IO */
+
+ /* Map FE-specific LUN ID into global one. */
+ io->io_hdr.nexus.targ_mapped_lun =
+ ctl_lun_map_from_port(port, io->io_hdr.nexus.targ_lun);
+
+ switch (io->io_hdr.io_type) {
+ case CTL_IO_SCSI:
+ if (ctl_debug & CTL_DEBUG_CDB)
+ ctl_io_print(io);
+ ctl_scsiio_precheck(&io->scsiio);
+ break;
+ case CTL_IO_TASK:
+ if (ctl_debug & CTL_DEBUG_CDB)
+ ctl_io_print(io);
+ ctl_run_task(io);
+ break;
+ default:
+ printf("ctl_run: unknown I/O type %d\n", io->io_hdr.io_type);
+ return (EINVAL);
+ }
+
+ return (CTL_RETVAL_COMPLETE);
+}
+
#ifdef CTL_IO_DELAY
static void
ctl_done_timer_wakeup(void *arg)
@@ -13384,7 +13417,7 @@ ctl_work_thread(void *arg)
if (io->io_hdr.io_type == CTL_IO_TASK)
ctl_run_task(io);
else
- ctl_scsiio_precheck(softc, &io->scsiio);
+ ctl_scsiio_precheck(&io->scsiio);
continue;
}
io = (union ctl_io *)STAILQ_FIRST(&thr->rtr_queue);
diff --git a/sys/cam/ctl/ctl_frontend.h b/sys/cam/ctl/ctl_frontend.h
index bdcb7a2e1abd..c9ab255cdde4 100644
--- a/sys/cam/ctl/ctl_frontend.h
+++ b/sys/cam/ctl/ctl_frontend.h
@@ -310,6 +310,13 @@ void ctl_port_offline(struct ctl_port *fe);
*/
int ctl_queue(union ctl_io *io);
+/*
+ * This routine starts execution of I/O and task management requests from
+ * the FETD to the CTL layer. May sleep. Returns 0 for success, non-zero
+ * for failure.
+ */
+int ctl_run(union ctl_io *io);
+
/*
* This routine is used if the front end interface doesn't support
* autosense (e.g. non-packetized parallel SCSI). This will queue the
diff --git a/sys/cam/ctl/ctl_frontend_ioctl.c b/sys/cam/ctl/ctl_frontend_ioctl.c
index 370e553042c5..ef5e2bd22a86 100644
--- a/sys/cam/ctl/ctl_frontend_ioctl.c
+++ b/sys/cam/ctl/ctl_frontend_ioctl.c
@@ -524,7 +524,7 @@ cfi_submit_wait(union ctl_io *io)
CTL_DEBUG_PRINT(("cfi_submit_wait\n"));
/* This shouldn't happen */
- if ((retval = ctl_queue(io)) != CTL_RETVAL_COMPLETE)
+ if ((retval = ctl_run(io)) != CTL_RETVAL_COMPLETE)
return (retval);
done = 0;
diff --git a/sys/cam/ctl/ctl_frontend_iscsi.c b/sys/cam/ctl/ctl_frontend_iscsi.c
index 8b0effcaf393..73483fb155cc 100644
--- a/sys/cam/ctl/ctl_frontend_iscsi.c
+++ b/sys/cam/ctl/ctl_frontend_iscsi.c
@@ -557,9 +557,9 @@ cfiscsi_pdu_handle_scsi_command(struct icl_pdu *request)
io->scsiio.cdb_len = sizeof(bhssc->bhssc_cdb); /* Which is 16. */
memcpy(io->scsiio.cdb, bhssc->bhssc_cdb, sizeof(bhssc->bhssc_cdb));
refcount_acquire(&cs->cs_outstanding_ctl_pdus);
- error = ctl_queue(io);
+ error = ctl_run(io);
if (error != CTL_RETVAL_COMPLETE) {
- CFISCSI_SESSION_WARN(cs, "ctl_queue() failed; error %d; "
+ CFISCSI_SESSION_WARN(cs, "ctl_run() failed; error %d; "
"dropping connection", error);
ctl_free_io(io);
refcount_release(&cs->cs_outstanding_ctl_pdus);
@@ -679,9 +679,9 @@ cfiscsi_pdu_handle_task_request(struct icl_pdu *request)
}
refcount_acquire(&cs->cs_outstanding_ctl_pdus);
- error = ctl_queue(io);
+ error = ctl_run(io);
if (error != CTL_RETVAL_COMPLETE) {
- CFISCSI_SESSION_WARN(cs, "ctl_queue() failed; error %d; "
+ CFISCSI_SESSION_WARN(cs, "ctl_run() failed; error %d; "
"dropping connection", error);
ctl_free_io(io);
refcount_release(&cs->cs_outstanding_ctl_pdus);
@@ -1128,9 +1128,9 @@ cfiscsi_session_terminate_tasks(struct cfiscsi_session *cs)
io->taskio.task_action = CTL_TASK_I_T_NEXUS_RESET;
wait = cs->cs_outstanding_ctl_pdus;
refcount_acquire(&cs->cs_outstanding_ctl_pdus);
- error = ctl_queue(io);
+ error = ctl_run(io);
if (error != CTL_RETVAL_COMPLETE) {
- CFISCSI_SESSION_WARN(cs, "ctl_queue() failed; error %d", error);
+ CFISCSI_SESSION_WARN(cs, "ctl_run() failed; error %d", error);
refcount_release(&cs->cs_outstanding_ctl_pdus);
ctl_free_io(io);
}
diff --git a/sys/cam/ctl/ctl_tpc.c b/sys/cam/ctl/ctl_tpc.c
index 456157749c89..5e6cb09760a7 100644
--- a/sys/cam/ctl/ctl_tpc.c
+++ b/sys/cam/ctl/ctl_tpc.c
@@ -1628,7 +1628,7 @@ tpc_done(union ctl_io *io)
io->io_hdr.flags &= ~CTL_FLAG_ABORT;
io->io_hdr.flags &= ~CTL_FLAG_SENT_2OTHER_SC;
if (tpcl_queue(io, tio->lun) != CTL_RETVAL_COMPLETE) {
- printf("%s: error returned from ctl_queue()!\n",
+ printf("%s: error returned from tpcl_queue()!\n",
__func__);
io->io_hdr.status = old_status;
} else
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