16 requests, it will let the depth drain down to 4 before starting to fill
it again.
+.. option:: serialize_overlap=bool
+
+ Serialize in-flight I/Os that might otherwise cause or suffer from data races.
+ When two or more I/Os are submitted simultaneously, there is no guarantee that
+ the I/Os will be processed or completed in the submitted order. Further, if
+ two or more of those I/Os are writes, any overlapping region between them can
+ become indeterminate/undefined on certain storage. These issues can cause
+ verification to fail erratically when at least one of the racing I/Os is
+ changing data and the overlapping region has a non-zero size. Setting
+ ``serialize_overlap`` tells fio to avoid provoking this behavior by explicitly
+ serializing in-flight I/Os that have a non-zero overlap. Note that setting
+ this option can reduce both performance and the `:option:iodepth` achieved.
+ Additionally this option does not work when :option:`io_submit_mode` is set to
+ offload. Default: false.
+
.. option:: io_submit_mode=str
This option controls how fio submits the I/O to the I/O engine. The default
Enable experimental verification.
-
Steady state
~~~~~~~~~~~~
return ret;
}
+/*
+ * Check if io_u will overlap an in-flight IO in the queue
+ */
+static bool in_flight_overlap(struct io_u_queue *q, struct io_u *io_u)
+{
+ bool overlap;
+ struct io_u *check_io_u;
+ unsigned long long x1, x2, y1, y2;
+ int i;
+
+ x1 = io_u->offset;
+ x2 = io_u->offset + io_u->buflen;
+ overlap = false;
+ io_u_qiter(q, check_io_u, i) {
+ if (check_io_u->flags & IO_U_F_FLIGHT) {
+ y1 = check_io_u->offset;
+ y2 = check_io_u->offset + check_io_u->buflen;
+
+ if (x1 < y2 && y1 < x2) {
+ overlap = true;
+ dprint(FD_IO, "in-flight overlap: %llu/%lu, %llu/%lu\n",
+ x1, io_u->buflen,
+ y1, check_io_u->buflen);
+ break;
+ }
+ }
+ }
+
+ return overlap;
+}
+
+static int io_u_submit(struct thread_data *td, struct io_u *io_u)
+{
+ /*
+ * Check for overlap if the user asked us to, and we have
+ * at least one IO in flight besides this one.
+ */
+ if (td->o.serialize_overlap && td->cur_depth > 1 &&
+ in_flight_overlap(&td->io_u_all, io_u))
+ return FIO_Q_BUSY;
+
+ return td_io_queue(td, io_u);
+}
+
/*
* The main verify engine. Runs over the writes we previously submitted,
* reads the blocks back in, and checks the crc/md5 of the data.
if (!td->o.disable_slat)
fio_gettime(&io_u->start_time, NULL);
- ret = td_io_queue(td, io_u);
+ ret = io_u_submit(td, io_u);
if (io_queue_event(td, io_u, &ret, ddir, NULL, 1, NULL))
break;
td->rate_next_io_time[ddir] = usec_for_io(td, ddir);
} else {
- ret = td_io_queue(td, io_u);
+ ret = io_u_submit(td, io_u);
if (should_check_rate(td))
td->rate_next_io_time[ddir] = usec_for_io(td, ddir);
o->iodepth_batch = le32_to_cpu(top->iodepth_batch);
o->iodepth_batch_complete_min = le32_to_cpu(top->iodepth_batch_complete_min);
o->iodepth_batch_complete_max = le32_to_cpu(top->iodepth_batch_complete_max);
+ o->serialize_overlap = le32_to_cpu(top->serialize_overlap);
o->size = le64_to_cpu(top->size);
o->io_size = le64_to_cpu(top->io_size);
o->size_percent = le32_to_cpu(top->size_percent);
top->iodepth_batch = cpu_to_le32(o->iodepth_batch);
top->iodepth_batch_complete_min = cpu_to_le32(o->iodepth_batch_complete_min);
top->iodepth_batch_complete_max = cpu_to_le32(o->iodepth_batch_complete_max);
+ top->serialize_overlap = cpu_to_le32(o->serialize_overlap);
top->size_percent = cpu_to_le32(o->size_percent);
top->fill_device = cpu_to_le32(o->fill_device);
top->file_append = cpu_to_le32(o->file_append);
Low watermark indicating when to start filling the queue again. Default:
\fBiodepth\fR.
.TP
+.BI serialize_overlap \fR=\fPbool
+Serialize in-flight I/Os that might otherwise cause or suffer from data races.
+When two or more I/Os are submitted simultaneously, there is no guarantee that
+the I/Os will be processed or completed in the submitted order. Further, if
+two or more of those I/Os are writes, any overlapping region between them can
+become indeterminate/undefined on certain storage. These issues can cause
+verification to fail erratically when at least one of the racing I/Os is
+changing data and the overlapping region has a non-zero size. Setting
+\fBserialize_overlap\fR tells fio to avoid provoking this behavior by explicitly
+serializing in-flight I/Os that have a non-zero overlap. Note that setting
+this option can reduce both performance and the \fBiodepth\fR achieved.
+Additionally this option does not work when \fBio_submit_mode\fR is set to
+offload. Default: false.
+.TP
.BI io_submit_mode \fR=\fPstr
This option controls how fio submits the IO to the IO engine. The default is
\fBinline\fR, which means that the fio job threads submit and reap IO directly.
if (o->iodepth_batch_complete_min > o->iodepth_batch_complete_max)
o->iodepth_batch_complete_max = o->iodepth_batch_complete_min;
+ /*
+ * There's no need to check for in-flight overlapping IOs if the job
+ * isn't changing data or the maximum iodepth is guaranteed to be 1
+ */
+ if (o->serialize_overlap && !(td->flags & TD_F_READ_IOLOG) &&
+ (!(td_write(td) || td_trim(td)) || o->iodepth == 1))
+ o->serialize_overlap = 0;
+ /*
+ * Currently can't check for overlaps in offload mode
+ */
+ if (o->serialize_overlap && o->io_submit_mode == IO_MODE_OFFLOAD) {
+ log_err("fio: checking for in-flight overlaps when the "
+ "io_submit_mode is offload is not supported\n");
+ o->serialize_overlap = 0;
+ ret = warnings_fatal;
+ }
+
if (o->nr_files > td->files_index)
o->nr_files = td->files_index;
}
/*
- * We don't need to sort the entries, if:
+ * We don't need to sort the entries if we only performed sequential
+ * writes. In this case, just reading back data in the order we wrote
+ * it out is the faster but still safe.
*
- * Sequential writes, or
- * Random writes that lay out the file as it goes along
- *
- * For both these cases, just reading back data in the order we
- * wrote it out is the fastest.
- *
- * One exception is if we don't have a random map AND we are doing
- * verifies, in that case we need to check for duplicate blocks and
- * drop the old one, which we rely on the rb insert/lookup for
- * handling.
+ * One exception is if we don't have a random map in which case we need
+ * to check for duplicate blocks and drop the old one, which we rely on
+ * the rb insert/lookup for handling.
*/
- if (((!td->o.verifysort) || !td_random(td) || !td->o.overwrite) &&
- (file_randommap(td, ipo->file) || td->o.verify == VERIFY_NONE)) {
+ if (((!td->o.verifysort) || !td_random(td)) &&
+ file_randommap(td, ipo->file)) {
INIT_FLIST_HEAD(&ipo->list);
flist_add_tail(&ipo->list, &td->io_hist_list);
ipo->flags |= IP_F_ONLIST;
td->io_hist_len--;
rb_erase(parent, &td->io_hist_tree);
remove_trim_entry(td, __ipo);
- free(__ipo);
+ if (!(__ipo->flags & IP_F_IN_FLIGHT))
+ free(__ipo);
goto restart;
}
}
.category = FIO_OPT_C_IO,
.group = FIO_OPT_G_IO_BASIC,
},
+ {
+ .name = "serialize_overlap",
+ .lname = "Serialize overlap",
+ .off1 = offsetof(struct thread_options, serialize_overlap),
+ .type = FIO_OPT_BOOL,
+ .help = "Wait for in-flight IOs that collide to complete",
+ .parent = "iodepth",
+ .def = "0",
+ .category = FIO_OPT_C_IO,
+ .group = FIO_OPT_G_IO_BASIC,
+ },
{
.name = "io_submit_mode",
.lname = "IO submit mode",
unsigned int iodepth_batch;
unsigned int iodepth_batch_complete_min;
unsigned int iodepth_batch_complete_max;
+ unsigned int serialize_overlap;
unsigned int unique_filename;
uint32_t iodepth_batch;
uint32_t iodepth_batch_complete_min;
uint32_t iodepth_batch_complete_max;
+ uint32_t serialize_overlap;
+ uint32_t pad3;
uint64_t size;
uint64_t io_size;
projects / fio.git / commitdiff