Recent changes (master)

Jens Axboe
2017-11-18T13:00:24Z

The following changes since commit adf075fa89a7f3bbb45237f1440de0583833bd80:

ioengines: remove pointless list initializations (2017-11-16 20:03:15 -0700)

are available in the git repository at:

git://git.kernel.dk/fio.git master

for you to fetch changes up to 40e5f1bf1aca5970528724873a4544c43712a75d:

Merge branch 'libpmem' (2017-11-17 09:21:19 -0700)

----------------------------------------------------------------
Jens Axboe (5):
Merge branch 'add-libpmem-engine' of https://github.com/tishizaki/fio into libpmem
libpmem: code cleanups
libpmem: move mmap alignment to init time
examples/libpmem.fio: clean up example
Merge branch 'libpmem'

Teruaki Ishizaki (1):
fio: add libpmem engine

HOWTO | 5 +
Makefile | 3 +
configure | 9 +
engines/libpmem.c | 591 +++++++++++++++++++++++++++++++++++++++++++++++++++
examples/libpmem.fio | 73 +++++++
fio.1 | 5 +
options.c | 5 +
7 files changed, 691 insertions(+)
create mode 100644 engines/libpmem.c
create mode 100644 examples/libpmem.fio

---

Diff of recent changes:

diff --git a/HOWTO b/HOWTO
index 419fa73..dce96bc 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1820,6 +1820,11 @@ I/O engine
set `filesize` so that all the accounting still occurs, but no
actual I/O will be done other than creating the file.

+ **libpmem**
+ Read and write using mmap I/O to a file on a filesystem
+ mounted with DAX on a persistent memory device through the NVML
+ libpmem library.
+
I/O engine specific parameters
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

diff --git a/Makefile b/Makefile
index 2893348..3ce6064 100644
--- a/Makefile
+++ b/Makefile
@@ -135,6 +135,9 @@ endif
ifdef CONFIG_LINUX_DEVDAX
SOURCE += engines/dev-dax.c
endif
+ifdef CONFIG_LIBPMEM
+ SOURCE += engines/libpmem.c
+endif

ifeq ($(CONFIG_TARGET_OS), Linux)
SOURCE += diskutil.c fifo.c blktrace.c cgroup.c trim.c engines/sg.c \
diff --git a/configure b/configure
index d34c000..31ba822 100755
--- a/configure
+++ b/configure
@@ -142,6 +142,7 @@ gfio_check="no"
libhdfs="no"
pmemblk="no"
devdax="no"
+pmem="no"
disable_lex=""
disable_pmem="no"
prefix=/usr/local
@@ -1845,6 +1846,7 @@ print_config "libpmemblk" "$libpmemblk"

# Choose the ioengines
if test "$libpmem" = "yes" && test "$disable_pmem" = "no"; then
+ pmem="yes"
devdax="yes"
if test "$libpmemblk" = "yes"; then
pmemblk="yes"
@@ -1860,6 +1862,10 @@ print_config "NVML pmemblk engine" "$pmemblk"
print_config "NVML dev-dax engine" "$devdax"

##########################################
+# Report whether libpmem engine is enabled
+print_config "NVML libpmem engine" "$pmem"
+
+##########################################
# Check if we have lex/yacc available
yacc="no"
yacc_is_bison="no"
@@ -2300,6 +2306,9 @@ fi
if test "$devdax" = "yes" ; then
output_sym "CONFIG_LINUX_DEVDAX"
fi
+if test "$pmem" = "yes" ; then
+ output_sym "CONFIG_LIBPMEM"
+fi
if test "$arith" = "yes" ; then
output_sym "CONFIG_ARITHMETIC"
if test "$yacc_is_bison" = "yes" ; then
diff --git a/engines/libpmem.c b/engines/libpmem.c
new file mode 100644
index 0000000..3f4e44f
--- /dev/null
+++ b/engines/libpmem.c
@@ -0,0 +1,591 @@
+/*
+ * libpmem: IO engine that uses NVML libpmem to read and write data
+ *
+ * Copyright (C) 2017 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License,
+ * version 2 as published by the Free Software Foundation..
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+/*
+ * libpmem engine
+ *
+ * IO engine that uses libpmem to read and write data
+ *
+ * To use:
+ * ioengine=libpmem
+ *
+ * Other relevant settings:
+ * iodepth=1
+ * direct=1
+ * directory=/mnt/pmem0/
+ * bs=4k
+ *
+ * direct=1 means that pmem_drain() is executed for each write operation.
+ * In contrast, direct=0 means that pmem_drain() is not executed.
+ *
+ * The pmem device must have a DAX-capable filesystem and be mounted
+ * with DAX enabled. directory must point to a mount point of DAX FS.
+ *
+ * Example:
+ * mkfs.xfs /dev/pmem0
+ * mkdir /mnt/pmem0
+ * mount -o dax /dev/pmem0 /mnt/pmem0
+ *
+ *
+ * See examples/libpmem.fio for more.
+ *
+ *
+ * libpmem.so
+ * By default, the libpmem engine will let the system find the libpmem.so
+ * that it uses. You can use an alternative libpmem by setting the
+ * FIO_PMEM_LIB environment variable to the full path to the desired
+ * libpmem.so.
+ */
+
+#include <stdio.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <libgen.h>
+#include <libpmem.h>
+
+#include "../fio.h"
+#include "../verify.h"
+
+/*
+ * Limits us to 1GiB of mapped files in total to model after
+ * libpmem engine behavior
+ */
+#define MMAP_TOTAL_SZ (1 * 1024 * 1024 * 1024UL)
+
+struct fio_libpmem_data {
+ void *libpmem_ptr;
+ size_t libpmem_sz;
+ off_t libpmem_off;
+};
+
+#define MEGABYTE ((uintptr_t)1 << 20)
+#define GIGABYTE ((uintptr_t)1 << 30)
+#define PROCMAXLEN 2048 /* maximum expected line length in /proc files */
+#define roundup(x, y) ((((x) + ((y) - 1)) / (y)) * (y))
+
+static bool Mmap_no_random;
+static void *Mmap_hint;
+static unsigned long long Mmap_align;
+
+/*
+ * util_map_hint_align -- choose the desired mapping alignment
+ *
+ * Use 2MB/1GB page alignment only if the mapping length is at least
+ * twice as big as the page size.
+ */
+static inline size_t util_map_hint_align(size_t len, size_t req_align)
+{
+ size_t align = Mmap_align;
+
+ dprint(FD_IO, "DEBUG util_map_hint_align\n" );
+
+ if (req_align)
+ align = req_align;
+ else if (len >= 2 * GIGABYTE)
+ align = GIGABYTE;
+ else if (len >= 4 * MEGABYTE)
+ align = 2 * MEGABYTE;
+
+ dprint(FD_IO, "align=%d\n", (int)align);
+ return align;
+}
+
+#ifdef __FreeBSD__
+static const char *sscanf_os = "%p %p";
+#define MAP_NORESERVE 0
+#define OS_MAPFILE "/proc/curproc/map"
+#else
+static const char *sscanf_os = "%p-%p";
+#define OS_MAPFILE "/proc/self/maps"
+#endif
+
+/*
+ * util_map_hint_unused -- use /proc to determine a hint address for mmap()
+ *
+ * This is a helper function for util_map_hint().
+ * It opens up /proc/self/maps and looks for the first unused address
+ * in the process address space that is:
+ * - greater or equal 'minaddr' argument,
+ * - large enough to hold range of given length,
+ * - aligned to the specified unit.
+ *
+ * Asking for aligned address like this will allow the DAX code to use large
+ * mappings. It is not an error if mmap() ignores the hint and chooses
+ * different address.
+ */
+static char *util_map_hint_unused(void *minaddr, size_t len, size_t align)
+{
+ char *lo = NULL; /* beginning of current range in maps file */
+ char *hi = NULL; /* end of current range in maps file */
+ char *raddr = minaddr; /* ignore regions below 'minaddr' */
+
+#ifdef WIN32
+ MEMORY_BASIC_INFORMATION mi;
+#else
+ FILE *fp;
+ char line[PROCMAXLEN]; /* for fgets() */
+#endif
+
+ dprint(FD_IO, "DEBUG util_map_hint_unused\n");
+ assert(align > 0);
+
+ if (raddr == NULL)
+ raddr += page_size;
+
+ raddr = (char *)roundup((uintptr_t)raddr, align);
+
+#ifdef WIN32
+ while ((uintptr_t)raddr < UINTPTR_MAX - len) {
+ size_t ret = VirtualQuery(raddr, &mi, sizeof(mi));
+ if (ret == 0) {
+ ERR("VirtualQuery %p", raddr);
+ return MAP_FAILED;
+ }
+ dprint(FD_IO, "addr %p len %zu state %d",
+ mi.BaseAddress, mi.RegionSize, mi.State);
+
+ if ((mi.State != MEM_FREE) || (mi.RegionSize < len)) {
+ raddr = (char *)mi.BaseAddress + mi.RegionSize;
+ raddr = (char *)roundup((uintptr_t)raddr, align);
+ dprint(FD_IO, "nearest aligned addr %p", raddr);
+ } else {
+ dprint(FD_IO, "unused region of size %zu found at %p",
+ mi.RegionSize, mi.BaseAddress);
+ return mi.BaseAddress;
+ }
+ }
+
+ dprint(FD_IO, "end of address space reached");
+ return MAP_FAILED;
+#else
+ fp = fopen(OS_MAPFILE, "r");
+ if (!fp) {
+ log_err("!%s\n", OS_MAPFILE);
+ return MAP_FAILED;
+ }
+
+ while (fgets(line, PROCMAXLEN, fp) != NULL) {
+ /* check for range line */
+ if (sscanf(line, sscanf_os, &lo, &hi) == 2) {
+ dprint(FD_IO, "%p-%p\n", lo, hi);
+ if (lo > raddr) {
+ if ((uintptr_t)(lo - raddr) >= len) {
+ dprint(FD_IO, "unused region of size "
+ "%zu found at %p\n",
+ lo - raddr, raddr);
+ break;
+ } else {
+ dprint(FD_IO, "region is too small: "
+ "%zu < %zu\n",
+ lo - raddr, len);
+ }
+ }
+
+ if (hi > raddr) {
+ raddr = (char *)roundup((uintptr_t)hi, align);
+ dprint(FD_IO, "nearest aligned addr %p\n",
+ raddr);
+ }
+
+ if (raddr == 0) {
+ dprint(FD_IO, "end of address space reached\n");
+ break;
+ }
+ }
+ }
+
+ /*
+ * Check for a case when this is the last unused range in the address
+ * space, but is not large enough. (very unlikely)
+ */
+ if ((raddr != NULL) && (UINTPTR_MAX - (uintptr_t)raddr < len)) {
+ dprint(FD_IO, "end of address space reached");
+ raddr = MAP_FAILED;
+ }
+
+ fclose(fp);
+
+ dprint(FD_IO, "returning %p", raddr);
+ return raddr;
+#endif
+}
+
+/*
+ * util_map_hint -- determine hint address for mmap()
+ *
+ * If PMEM_MMAP_HINT environment variable is not set, we let the system to pick
+ * the randomized mapping address. Otherwise, a user-defined hint address
+ * is used.
+ *
+ * Windows Environment:
+ * XXX - Windows doesn't support large DAX pages yet, so there is
+ * no point in aligning for the same.
+ *
+ * Except for Windows Environment:
+ * ALSR in 64-bit Linux kernel uses 28-bit of randomness for mmap
+ * (bit positions 12-39), which means the base mapping address is randomized
+ * within [0..1024GB] range, with 4KB granularity. Assuming additional
+ * 1GB alignment, it results in 1024 possible locations.
+ *
+ * Configuring the hint address via PMEM_MMAP_HINT environment variable
+ * disables address randomization. In such case, the function will search for
+ * the first unused, properly aligned region of given size, above the
+ * specified address.
+ */
+static char *util_map_hint(size_t len, size_t req_align)
+{
+ char *addr;
+ size_t align = 0;
+ char *e = NULL;
+
+ dprint(FD_IO, "DEBUG util_map_hint\n");
+ dprint(FD_IO, "len %zu req_align %zu\n", len, req_align);
+
+ /* choose the desired alignment based on the requested length */
+ align = util_map_hint_align(len, req_align);
+
+ e = getenv("PMEM_MMAP_HINT");
+ if (e) {
+ char *endp;
+ unsigned long long val = 0;
+
+ errno = 0;
+
+ val = strtoull(e, &endp, 16);
+ if (errno || endp == e) {
+ dprint(FD_IO, "Invalid PMEM_MMAP_HINT\n");
+ } else {
+ Mmap_hint = (void *)val;
+ Mmap_no_random = true;
+ dprint(FD_IO, "PMEM_MMAP_HINT set to %p\n", Mmap_hint);
+ }
+ }
+
+ if (Mmap_no_random) {
+ dprint(FD_IO, "user-defined hint %p\n", (void *)Mmap_hint);
+ addr = util_map_hint_unused((void *)Mmap_hint, len, align);
+ } else {
+ /*
+ * Create dummy mapping to find an unused region of given size.
+ * * Request for increased size for later address alignment.
+ *
+ * Windows Environment:
+ * Use MAP_NORESERVE flag to only reserve the range of pages
+ * rather than commit. We don't want the pages to be actually
+ * backed by the operating system paging file, as the swap
+ * file is usually too small to handle terabyte pools.
+ *
+ * Except for Windows Environment:
+ * Use MAP_PRIVATE with read-only access to simulate
+ * zero cost for overcommit accounting. Note: MAP_NORESERVE
+ * flag is ignored if overcommit is disabled (mode 2).
+ */
+#ifndef WIN32
+ addr = mmap(NULL, len + align, PROT_READ,
+ MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+#else
+ addr = mmap(NULL, len + align, PROT_READ,
+ MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0);
+#endif
+ if (addr != MAP_FAILED) {
+ dprint(FD_IO, "system choice %p\n", addr);
+ munmap(addr, len + align);
+ addr = (char *)roundup((uintptr_t)addr, align);
+ }
+ }
+
+ dprint(FD_IO, "hint %p\n", addr);
+
+ return addr;
+}
+
+/*
+ * This is the mmap execution function
+ */
+static int fio_libpmem_file(struct thread_data *td, struct fio_file *f,
+ size_t length, off_t off)
+{
+ struct fio_libpmem_data *fdd = FILE_ENG_DATA(f);
+ int flags = 0;
+ void *addr = NULL;
+
+ dprint(FD_IO, "DEBUG fio_libpmem_file\n");
+
+ if (td_rw(td))
+ flags = PROT_READ | PROT_WRITE;
+ else if (td_write(td)) {
+ flags = PROT_WRITE;
+
+ if (td->o.verify != VERIFY_NONE)
+ flags |= PROT_READ;
+ } else
+ flags = PROT_READ;
+
+ dprint(FD_IO, "f->file_name = %s td->o.verify = %d \n", f->file_name,
+ td->o.verify);
+ dprint(FD_IO, "length = %ld flags = %d f->fd = %d off = %ld \n",
+ length, flags, f->fd,off);
+
+ addr = util_map_hint(length, 0);
+
+ fdd->libpmem_ptr = mmap(addr, length, flags, MAP_SHARED, f->fd, off);
+ if (fdd->libpmem_ptr == MAP_FAILED) {
+ fdd->libpmem_ptr = NULL;
+ td_verror(td, errno, "mmap");
+ }
+
+ if (td->error && fdd->libpmem_ptr)
+ munmap(fdd->libpmem_ptr, length);
+
+ return td->error;
+}
+
+/*
+ * XXX Just mmap an appropriate portion, we cannot mmap the full extent
+ */
+static int fio_libpmem_prep_limited(struct thread_data *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+ struct fio_libpmem_data *fdd = FILE_ENG_DATA(f);
+
+ dprint(FD_IO, "DEBUG fio_libpmem_prep_limited\n" );
+
+ if (io_u->buflen > f->real_file_size) {
+ log_err("libpmem: bs too big for libpmem engine\n");
+ return EIO;
+ }
+
+ fdd->libpmem_sz = min(MMAP_TOTAL_SZ, f->real_file_size);
+ if (fdd->libpmem_sz > f->io_size)
+ fdd->libpmem_sz = f->io_size;
+
+ fdd->libpmem_off = io_u->offset;
+
+ return fio_libpmem_file(td, f, fdd->libpmem_sz, fdd->libpmem_off);
+}
+
+/*
+ * Attempt to mmap the entire file
+ */
+static int fio_libpmem_prep_full(struct thread_data *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+ struct fio_libpmem_data *fdd = FILE_ENG_DATA(f);
+ int ret;
+
+ dprint(FD_IO, "DEBUG fio_libpmem_prep_full\n" );
+
+ if (fio_file_partial_mmap(f))
+ return EINVAL;
+
+ dprint(FD_IO," f->io_size %ld : io_u->offset %lld \n",
+ f->io_size, io_u->offset);
+
+ if (io_u->offset != (size_t) io_u->offset ||
+ f->io_size != (size_t) f->io_size) {
+ fio_file_set_partial_mmap(f);
+ return EINVAL;
+ }
+ fdd->libpmem_sz = f->io_size;
+ fdd->libpmem_off = 0;
+
+ ret = fio_libpmem_file(td, f, fdd->libpmem_sz, fdd->libpmem_off);
+ if (ret)
+ fio_file_set_partial_mmap(f);
+
+ return ret;
+}
+
+static int fio_libpmem_prep(struct thread_data *td, struct io_u *io_u)
+{
+ struct fio_file *f = io_u->file;
+ struct fio_libpmem_data *fdd = FILE_ENG_DATA(f);
+ int ret;
+
+ dprint(FD_IO, "DEBUG fio_libpmem_prep\n" );
+ /*
+ * It fits within existing mapping, use it
+ */
+ dprint(FD_IO," io_u->offset %lld : fdd->libpmem_off %ld : "
+ "io_u->buflen %ld : fdd->libpmem_sz %ld\n",
+ io_u->offset, fdd->libpmem_off,
+ io_u->buflen, fdd->libpmem_sz);
+
+ if (io_u->offset >= fdd->libpmem_off &&
+ (io_u->offset + io_u->buflen <
+ fdd->libpmem_off + fdd->libpmem_sz))
+ goto done;
+
+ /*
+ * unmap any existing mapping
+ */
+ if (fdd->libpmem_ptr) {
+ dprint(FD_IO,"munmap \n");
+ if (munmap(fdd->libpmem_ptr, fdd->libpmem_sz) < 0)
+ return errno;
+ fdd->libpmem_ptr = NULL;
+ }
+
+ if (fio_libpmem_prep_full(td, io_u)) {
+ td_clear_error(td);
+ ret = fio_libpmem_prep_limited(td, io_u);
+ if (ret)
+ return ret;
+ }
+
+done:
+ io_u->mmap_data = fdd->libpmem_ptr + io_u->offset - fdd->libpmem_off
+ - f->file_offset;
+ return 0;
+}
+
+static int fio_libpmem_queue(struct thread_data *td, struct io_u *io_u)
+{
+ fio_ro_check(td, io_u);
+ io_u->error = 0;
+
+ dprint(FD_IO, "DEBUG fio_libpmem_queue\n");
+
+ switch (io_u->ddir) {
+ case DDIR_READ:
+ memcpy(io_u->xfer_buf, io_u->mmap_data, io_u->xfer_buflen);
+ break;
+ case DDIR_WRITE:
+ dprint(FD_IO, "DEBUG mmap_data=%p, xfer_buf=%p\n",
+ io_u->mmap_data, io_u->xfer_buf );
+ dprint(FD_IO,"td->o.odirect %d \n",td->o.odirect);
+ if (td->o.odirect) {
+ pmem_memcpy_persist(io_u->mmap_data,
+ io_u->xfer_buf,
+ io_u->xfer_buflen);
+ } else {
+ pmem_memcpy_nodrain(io_u->mmap_data,
+ io_u->xfer_buf,
+ io_u->xfer_buflen);
+ }
+ break;
+ case DDIR_SYNC:
+ case DDIR_DATASYNC:
+ case DDIR_SYNC_FILE_RANGE:
+ break;
+ default:
+ io_u->error = EINVAL;
+ break;
+ }
+
+ return FIO_Q_COMPLETED;
+}
+
+static int fio_libpmem_init(struct thread_data *td)
+{
+ struct thread_options *o = &td->o;
+
+ dprint(FD_IO,"o->rw_min_bs %d \n o->fsync_blocks %d \n o->fdatasync_blocks %d \n",
+ o->rw_min_bs,o->fsync_blocks,o->fdatasync_blocks);
+ dprint(FD_IO, "DEBUG fio_libpmem_init\n");
+
+ if ((o->rw_min_bs & page_mask) &&
+ (o->fsync_blocks || o->fdatasync_blocks)) {
+ log_err("libpmem: mmap options dictate a minimum block size of "
+ "%llu bytes\n", (unsigned long long) page_size);
+ return 1;
+ }
+ return 0;
+}
+
+static int fio_libpmem_open_file(struct thread_data *td, struct fio_file *f)
+{
+ struct fio_libpmem_data *fdd;
+ int ret;
+
+ dprint(FD_IO,"DEBUG fio_libpmem_open_file\n");
+ dprint(FD_IO,"f->io_size=%ld \n",f->io_size);
+ dprint(FD_IO,"td->o.size=%lld \n",td->o.size);
+ dprint(FD_IO,"td->o.iodepth=%d\n",td->o.iodepth);
+ dprint(FD_IO,"td->o.iodepth_batch=%d \n",td->o.iodepth_batch);
+
+ ret = generic_open_file(td, f);
+ if (ret)
+ return ret;
+
+ fdd = calloc(1, sizeof(*fdd));
+ if (!fdd) {
+ int fio_unused __ret;
+ __ret = generic_close_file(td, f);
+ return 1;
+ }
+
+ FILE_SET_ENG_DATA(f, fdd);
+
+ return 0;
+}
+
+static int fio_libpmem_close_file(struct thread_data *td, struct fio_file *f)
+{
+ struct fio_libpmem_data *fdd = FILE_ENG_DATA(f);
+
+ dprint(FD_IO,"DEBUG fio_libpmem_close_file\n");
+ dprint(FD_IO,"td->o.odirect %d \n",td->o.odirect);
+
+ if (!td->o.odirect) {
+ dprint(FD_IO,"pmem_drain\n");
+ pmem_drain();
+ }
+
+ FILE_SET_ENG_DATA(f, NULL);
+ free(fdd);
+ fio_file_clear_partial_mmap(f);
+
+ return generic_close_file(td, f);
+}
+
+static struct ioengine_ops ioengine = {
+ .name = "libpmem",
+ .version = FIO_IOOPS_VERSION,
+ .init = fio_libpmem_init,
+ .prep = fio_libpmem_prep,
+ .queue = fio_libpmem_queue,
+ .open_file = fio_libpmem_open_file,
+ .close_file = fio_libpmem_close_file,
+ .get_file_size = generic_get_file_size,
+ .flags = FIO_SYNCIO |FIO_NOEXTEND,
+};
+
+static void fio_init fio_libpmem_register(void)
+{
+#ifndef WIN32
+ Mmap_align = page_size;
+#else
+ if (Mmap_align == 0) {
+ SYSTEM_INFO si;
+
+ GetSystemInfo(&si);
+ Mmap_align = si.dwAllocationGranularity;
+ }
+#endif
+
+ register_ioengine(&ioengine);
+}
+
+static void fio_exit fio_libpmem_unregister(void)
+{
+ unregister_ioengine(&ioengine);
+}
diff --git a/examples/libpmem.fio b/examples/libpmem.fio
new file mode 100644
index 0000000..d44fcfa
--- /dev/null
+++ b/examples/libpmem.fio
@@ -0,0 +1,73 @@
+[global]
+bs=4k
+size=8g
+ioengine=libpmem
+norandommap
+time_based=1
+group_reporting
+invalidate=1
+disable_lat=1
+disable_slat=1
+disable_clat=1
+clat_percentiles=0
+
+iodepth=1
+iodepth_batch=1
+thread=1
+numjobs=1
+
+#
+# In case of 'scramble_buffers=1', the source buffer
+# is rewritten with a random value every write operations.
+#
+# But when 'scramble_buffers=0' is set, the source buffer isn't
+# rewritten. So it will be likely that the source buffer is in CPU
+# cache and it seems to be high performance.
+#
+scramble_buffers=0
+
+#
+# direct=0:
+# Using pmem_memcpy_nodrain() for write operation
+#
+# direct=1:
+# Using pmem_memcpy_persist() for write operation
+#
+direct=0
+
+#
+# Setting for fio process's CPU Node and Memory Node
+#
+numa_cpu_nodes=0
+numa_mem_policy=bind:0
+
+#
+# split means that each job will get a unique CPU from the CPU set
+#
+cpus_allowed_policy=split
+
+#
+# The pmemblk engine does IO to files in a DAX-mounted filesystem.
+# The filesystem should be created on an NVDIMM (e.g /dev/pmem0)
+# and then mounted with the '-o dax' option. Note that the engine
+# accesses the underlying NVDIMM directly, bypassing the kernel block
+# layer, so the usual filesystem/disk performance monitoring tools such
+# as iostat will not provide useful data.
+#
+directory=/mnt/pmem0
+
+[libpmem-seqwrite]
+rw=write
+stonewall
+
+#[libpmem-seqread]
+#rw=read
+#stonewall
+
+#[libpmem-randwrite]
+#rw=randwrite
+#stonewall
+
+#[libpmem-randread]
+#rw=randread
+#stonewall
diff --git a/fio.1 b/fio.1
index 1f9fffc..bd7670a 100644
--- a/fio.1
+++ b/fio.1
@@ -1597,6 +1597,11 @@ details of writing an external I/O engine.
Simply create the files and do no I/O to them. You still need to set
\fBfilesize\fR so that all the accounting still occurs, but no actual I/O will be
done other than creating the file.
+.TP
+.B libpmem
+Read and write using mmap I/O to a file on a filesystem
+mounted with DAX on a persistent memory device through the NVML
+libpmem library.
.SS "I/O engine specific parameters"
In addition, there are some parameters which are only valid when a specific
\fBioengine\fR is in use. These are used identically to normal parameters,
diff --git a/options.c b/options.c
index e8d1a3a..a0fcd8f 100644
--- a/options.c
+++ b/options.c
@@ -1851,6 +1851,11 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
.help = "Load external engine (append name)",
.cb = str_ioengine_external_cb,
},
+#ifdef CONFIG_LIBPMEM
+ { .ival = "libpmem",
+ .help = "NVML libpmem based IO engine",
+ },
+#endif
},
},
{