[PATCH 030/124] staging: lustre: llite: Replace write mutex with range lock
From: James Simmons
Date: Sun Sep 18 2016 - 17:04:05 EST
From: Prakash Surya <surya1@xxxxxxxx>
Testing has shown the ll_inode_inode's lli_write_mutex to be a
limiting factor with single shared file write performance, when using
many writing threads on a single machine. Even if each thread is
writing to a unique portion of the file, the lli_write_mutex will
prevent no more than a single thread to ever write to the file
simultaneously.
This change attempts to remove this bottle neck, by replacing this
mutex with a range lock. This should allow multiple threads to write
to a single file simultaneously iff the threads are writing to unique
regions of the file.
Performance testing shows this change to garner a significant
performance boost to write bandwidth. Using FIO on a single machine
with 32 GB of RAM, write performance tests were run with and without
this change applied; the results are below:
+---------+-----------+---------+--------+--------+--------+
| fio v2.0.13 | Write Bandwidth (KB/s) |
+---------+-----------+---------+--------+--------+--------+
| # Tasks | GB / Task | Test 1 | Test 2 | Test 3 | Test 4 |
+---------+-----------+---------+--------+--------+--------+
| 1 | 64 | 452446 | 454623 | 457653 | 463737 |
| 2 | 32 | 850318 | 565373 | 602498 | 733027 |
| 4 | 16 | 1058900 | 463546 | 529107 | 976284 |
| 8 | 8 | 1026300 | 468190 | 576451 | 963404 |
| 16 | 4 | 1065500 | 503160 | 462902 | 830065 |
| 32 | 2 | 1068600 | 462228 | 466963 | 749733 |
| 64 | 1 | 991830 | 556618 | 557863 | 710912 |
+---------+-----------+---------+--------+--------+--------+
* Test 1: Lustre client running 04ec54f. File per process write
workload. This test was used as a baseline for what we
_could_ achieve in the single shared file tests if the
bottle necks were removed.
* Test 2: Lustre client running 04ec54f. Single shared file
workload, each task writing to a unique region.
* Test 3: Lustre client running 04ec54f + I0023132b. Single shared
file workload, each task writing to a unique region.
* Test 4: Lustre client running 04ec54f + this patch.
Single shared file workload, each task writing to a unique
region.
Direct IO does not use the page cache like normal IO, so
concurrent direct IO reads of the same pages are not safe.
As a result, direct IO reads must take the range lock
in ll_file_io_generic, otherwise they will attempt to work
on the same pages and hit assertions like:
(osc_request.c:1219:osc_brw_prep_request())
ASSERTION( i == 0 || pg->off > pg_prev->off ) failed:
i 3 p_c 10 pg ffffea00017a5208 [pri 0 ind 2771] off 16384
prev_pg ffffea00017a51d0 [pri 0 ind 2256] off 16384
Signed-off-by: Prakash Surya <surya1@xxxxxxxx>
Signed-off-by: Patrick Farrell <paf@xxxxxxxx>
Signed-off-by: Jinshan Xiong <jinshan.xiong@xxxxxxxxx>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-1669
Reviewed-on: http://review.whamcloud.com/6320
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-6227
Reviewed-on: http://review.whamcloud.com/14385
Reviewed-by: Bobi Jam <bobijam@xxxxxxxxxxx>
Reviewed-by: Alexander Boyko <alexander.boyko@xxxxxxxxxxx>
Reviewed-by: Hiroya Nozaki <nozaki.hiroya@xxxxxxxxxxxxxx>
Reviewed-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
Reviewed-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Signed-off-by: James Simmons <jsimmons@xxxxxxxxxxxxx>
---
drivers/staging/lustre/lustre/llite/Makefile | 2 +-
drivers/staging/lustre/lustre/llite/file.c | 37 +++-
.../staging/lustre/lustre/llite/llite_internal.h | 5 +-
drivers/staging/lustre/lustre/llite/llite_lib.c | 2 +-
drivers/staging/lustre/lustre/llite/range_lock.c | 233 ++++++++++++++++++++
drivers/staging/lustre/lustre/llite/range_lock.h | 82 +++++++
6 files changed, 348 insertions(+), 13 deletions(-)
create mode 100644 drivers/staging/lustre/lustre/llite/range_lock.c
create mode 100644 drivers/staging/lustre/lustre/llite/range_lock.h
diff --git a/drivers/staging/lustre/lustre/llite/Makefile b/drivers/staging/lustre/lustre/llite/Makefile
index 2cbb1b8..1ac0940 100644
--- a/drivers/staging/lustre/lustre/llite/Makefile
+++ b/drivers/staging/lustre/lustre/llite/Makefile
@@ -1,6 +1,6 @@
obj-$(CONFIG_LUSTRE_FS) += lustre.o
lustre-y := dcache.o dir.o file.o llite_close.o llite_lib.o llite_nfs.o \
- rw.o namei.o symlink.o llite_mmap.o \
+ rw.o namei.o symlink.o llite_mmap.o range_lock.o \
xattr.o xattr_cache.o rw26.o super25.o statahead.o \
glimpse.o lcommon_cl.o lcommon_misc.o \
vvp_dev.o vvp_page.o vvp_lock.o vvp_io.o vvp_object.o vvp_req.o \
diff --git a/drivers/staging/lustre/lustre/llite/file.c b/drivers/staging/lustre/lustre/llite/file.c
index 273b563..d9ee255 100644
--- a/drivers/staging/lustre/lustre/llite/file.c
+++ b/drivers/staging/lustre/lustre/llite/file.c
@@ -1126,6 +1126,7 @@ ll_file_io_generic(const struct lu_env *env, struct vvp_io_args *args,
{
struct ll_inode_info *lli = ll_i2info(file_inode(file));
struct ll_file_data *fd = LUSTRE_FPRIVATE(file);
+ struct range_lock range;
struct cl_io *io;
ssize_t result;
@@ -1138,7 +1139,12 @@ restart:
if (cl_io_rw_init(env, io, iot, *ppos, count) == 0) {
struct vvp_io *vio = vvp_env_io(env);
- int write_mutex_locked = 0;
+ bool range_locked = false;
+
+ if (file->f_flags & O_APPEND)
+ range_lock_init(&range, 0, LUSTRE_EOF);
+ else
+ range_lock_init(&range, *ppos, *ppos + count - 1);
vio->vui_fd = LUSTRE_FPRIVATE(file);
vio->vui_io_subtype = args->via_io_subtype;
@@ -1147,14 +1153,23 @@ restart:
case IO_NORMAL:
vio->vui_iter = args->u.normal.via_iter;
vio->vui_iocb = args->u.normal.via_iocb;
- if ((iot == CIT_WRITE) &&
+ /*
+ * Direct IO reads must also take range lock,
+ * or multiple reads will try to work on the same pages
+ * See LU-6227 for details.
+ */
+ if (((iot == CIT_WRITE) ||
+ (iot == CIT_READ && (file->f_flags & O_DIRECT))) &&
!(vio->vui_fd->fd_flags & LL_FILE_GROUP_LOCKED)) {
- if (mutex_lock_interruptible(&lli->
- lli_write_mutex)) {
- result = -ERESTARTSYS;
+ CDEBUG(D_VFSTRACE, "Range lock [%llu, %llu]\n",
+ range.rl_node.in_extent.start,
+ range.rl_node.in_extent.end);
+ result = range_lock(&lli->lli_write_tree,
+ &range);
+ if (result < 0)
goto out;
- }
- write_mutex_locked = 1;
+
+ range_locked = true;
}
down_read(&lli->lli_trunc_sem);
break;
@@ -1171,8 +1186,12 @@ restart:
ll_cl_remove(file, env);
if (args->via_io_subtype == IO_NORMAL)
up_read(&lli->lli_trunc_sem);
- if (write_mutex_locked)
- mutex_unlock(&lli->lli_write_mutex);
+ if (range_locked) {
+ CDEBUG(D_VFSTRACE, "Range unlock [%llu, %llu]\n",
+ range.rl_node.in_extent.start,
+ range.rl_node.in_extent.end);
+ range_unlock(&lli->lli_write_tree, &range);
+ }
} else {
/* cl_io_rw_init() handled IO */
result = io->ci_result;
diff --git a/drivers/staging/lustre/lustre/llite/llite_internal.h b/drivers/staging/lustre/lustre/llite/llite_internal.h
index f903f2a..7f0a6c9 100644
--- a/drivers/staging/lustre/lustre/llite/llite_internal.h
+++ b/drivers/staging/lustre/lustre/llite/llite_internal.h
@@ -46,6 +46,7 @@
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include "vvp_internal.h"
+#include "range_lock.h"
#ifndef FMODE_EXEC
#define FMODE_EXEC 0
@@ -210,7 +211,7 @@ struct ll_inode_info {
* }
*/
struct rw_semaphore f_trunc_sem;
- struct mutex f_write_mutex;
+ struct range_lock_tree f_write_tree;
struct rw_semaphore f_glimpse_sem;
unsigned long f_glimpse_time;
@@ -235,7 +236,7 @@ struct ll_inode_info {
#define lli_symlink_name u.f.f_symlink_name
#define lli_maxbytes u.f.f_maxbytes
#define lli_trunc_sem u.f.f_trunc_sem
-#define lli_write_mutex u.f.f_write_mutex
+#define lli_write_tree u.f.f_write_tree
#define lli_glimpse_sem u.f.f_glimpse_sem
#define lli_glimpse_time u.f.f_glimpse_time
#define lli_agl_list u.f.f_agl_list
diff --git a/drivers/staging/lustre/lustre/llite/llite_lib.c b/drivers/staging/lustre/lustre/llite/llite_lib.c
index 93fd69b..9112fa8 100644
--- a/drivers/staging/lustre/lustre/llite/llite_lib.c
+++ b/drivers/staging/lustre/lustre/llite/llite_lib.c
@@ -807,7 +807,7 @@ void ll_lli_init(struct ll_inode_info *lli)
mutex_init(&lli->lli_size_mutex);
lli->lli_symlink_name = NULL;
init_rwsem(&lli->lli_trunc_sem);
- mutex_init(&lli->lli_write_mutex);
+ range_lock_tree_init(&lli->lli_write_tree);
init_rwsem(&lli->lli_glimpse_sem);
lli->lli_glimpse_time = 0;
INIT_LIST_HEAD(&lli->lli_agl_list);
diff --git a/drivers/staging/lustre/lustre/llite/range_lock.c b/drivers/staging/lustre/lustre/llite/range_lock.c
new file mode 100644
index 0000000..94c818f
--- /dev/null
+++ b/drivers/staging/lustre/lustre/llite/range_lock.c
@@ -0,0 +1,233 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * 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 version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.gnu.org/licenses/gpl-2.0.html
+ *
+ * GPL HEADER END
+ */
+/*
+ * Range lock is used to allow multiple threads writing a single shared
+ * file given each thread is writing to a non-overlapping portion of the
+ * file.
+ *
+ * Refer to the possible upstream kernel version of range lock by
+ * Jan Kara <jack@xxxxxxx>: https://lkml.org/lkml/2013/1/31/480
+ *
+ * This file could later replaced by the upstream kernel version.
+ */
+/*
+ * Author: Prakash Surya <surya1@xxxxxxxx>
+ * Author: Bobi Jam <bobijam.xu@xxxxxxxxx>
+ */
+#include "range_lock.h"
+#include "../include/lustre/lustre_user.h"
+
+/**
+ * Initialize a range lock tree
+ *
+ * \param tree [in] an empty range lock tree
+ *
+ * Pre: Caller should have allocated the range lock tree.
+ * Post: The range lock tree is ready to function.
+ */
+void range_lock_tree_init(struct range_lock_tree *tree)
+{
+ tree->rlt_root = NULL;
+ tree->rlt_sequence = 0;
+ spin_lock_init(&tree->rlt_lock);
+}
+
+/**
+ * Initialize a range lock node
+ *
+ * \param lock [in] an empty range lock node
+ * \param start [in] start of the covering region
+ * \param end [in] end of the covering region
+ *
+ * Pre: Caller should have allocated the range lock node.
+ * Post: The range lock node is meant to cover [start, end] region
+ */
+void range_lock_init(struct range_lock *lock, __u64 start, __u64 end)
+{
+ memset(&lock->rl_node, 0, sizeof(lock->rl_node));
+ if (end != LUSTRE_EOF)
+ end >>= PAGE_SHIFT;
+ interval_set(&lock->rl_node, start >> PAGE_SHIFT, end);
+ INIT_LIST_HEAD(&lock->rl_next_lock);
+ lock->rl_task = NULL;
+ lock->rl_lock_count = 0;
+ lock->rl_blocking_ranges = 0;
+ lock->rl_sequence = 0;
+}
+
+static inline struct range_lock *next_lock(struct range_lock *lock)
+{
+ return list_entry(lock->rl_next_lock.next, typeof(*lock), rl_next_lock);
+}
+
+/**
+ * Helper function of range_unlock()
+ *
+ * \param node [in] a range lock found overlapped during interval node
+ * search
+ * \param arg [in] the range lock to be tested
+ *
+ * \retval INTERVAL_ITER_CONT indicate to continue the search for next
+ * overlapping range node
+ * \retval INTERVAL_ITER_STOP indicate to stop the search
+ */
+static enum interval_iter range_unlock_cb(struct interval_node *node, void *arg)
+{
+ struct range_lock *lock = arg;
+ struct range_lock *overlap = node2rangelock(node);
+ struct range_lock *iter;
+
+ list_for_each_entry(iter, &overlap->rl_next_lock, rl_next_lock) {
+ if (iter->rl_sequence > lock->rl_sequence) {
+ --iter->rl_blocking_ranges;
+ LASSERT(iter->rl_blocking_ranges > 0);
+ }
+ }
+ if (overlap->rl_sequence > lock->rl_sequence) {
+ --overlap->rl_blocking_ranges;
+ if (overlap->rl_blocking_ranges == 0)
+ wake_up_process(overlap->rl_task);
+ }
+ return INTERVAL_ITER_CONT;
+}
+
+/**
+ * Unlock a range lock, wake up locks blocked by this lock.
+ *
+ * \param tree [in] range lock tree
+ * \param lock [in] range lock to be deleted
+ *
+ * If this lock has been granted, relase it; if not, just delete it from
+ * the tree or the same region lock list. Wake up those locks only blocked
+ * by this lock through range_unlock_cb().
+ */
+void range_unlock(struct range_lock_tree *tree, struct range_lock *lock)
+{
+ spin_lock(&tree->rlt_lock);
+ if (!list_empty(&lock->rl_next_lock)) {
+ struct range_lock *next;
+
+ if (interval_is_intree(&lock->rl_node)) { /* first lock */
+ /* Insert the next same range lock into the tree */
+ next = next_lock(lock);
+ next->rl_lock_count = lock->rl_lock_count - 1;
+ interval_erase(&lock->rl_node, &tree->rlt_root);
+ interval_insert(&next->rl_node, &tree->rlt_root);
+ } else {
+ /* find the first lock in tree */
+ list_for_each_entry(next, &lock->rl_next_lock,
+ rl_next_lock) {
+ if (!interval_is_intree(&next->rl_node))
+ continue;
+
+ LASSERT(next->rl_lock_count > 0);
+ next->rl_lock_count--;
+ break;
+ }
+ }
+ list_del_init(&lock->rl_next_lock);
+ } else {
+ LASSERT(interval_is_intree(&lock->rl_node));
+ interval_erase(&lock->rl_node, &tree->rlt_root);
+ }
+
+ interval_search(tree->rlt_root, &lock->rl_node.in_extent,
+ range_unlock_cb, lock);
+ spin_unlock(&tree->rlt_lock);
+}
+
+/**
+ * Helper function of range_lock()
+ *
+ * \param node [in] a range lock found overlapped during interval node
+ * search
+ * \param arg [in] the range lock to be tested
+ *
+ * \retval INTERVAL_ITER_CONT indicate to continue the search for next
+ * overlapping range node
+ * \retval INTERVAL_ITER_STOP indicate to stop the search
+ */
+static enum interval_iter range_lock_cb(struct interval_node *node, void *arg)
+{
+ struct range_lock *lock = (struct range_lock *)arg;
+ struct range_lock *overlap = node2rangelock(node);
+
+ lock->rl_blocking_ranges += overlap->rl_lock_count + 1;
+ return INTERVAL_ITER_CONT;
+}
+
+/**
+ * Lock a region
+ *
+ * \param tree [in] range lock tree
+ * \param lock [in] range lock node containing the region span
+ *
+ * \retval 0 get the range lock
+ * \retval <0 error code while not getting the range lock
+ *
+ * If there exists overlapping range lock, the new lock will wait and
+ * retry, if later it find that it is not the chosen one to wake up,
+ * it wait again.
+ */
+int range_lock(struct range_lock_tree *tree, struct range_lock *lock)
+{
+ struct interval_node *node;
+ int rc = 0;
+
+ spin_lock(&tree->rlt_lock);
+ /*
+ * We need to check for all conflicting intervals
+ * already in the tree.
+ */
+ interval_search(tree->rlt_root, &lock->rl_node.in_extent,
+ range_lock_cb, lock);
+ /*
+ * Insert to the tree if I am unique, otherwise I've been linked to
+ * the rl_next_lock of another lock which has the same range as mine
+ * in range_lock_cb().
+ */
+ node = interval_insert(&lock->rl_node, &tree->rlt_root);
+ if (node) {
+ struct range_lock *tmp = node2rangelock(node);
+
+ list_add_tail(&lock->rl_next_lock, &tmp->rl_next_lock);
+ tmp->rl_lock_count++;
+ }
+ lock->rl_sequence = ++tree->rlt_sequence;
+
+ while (lock->rl_blocking_ranges > 0) {
+ lock->rl_task = current;
+ __set_current_state(TASK_INTERRUPTIBLE);
+ spin_unlock(&tree->rlt_lock);
+ schedule();
+
+ if (signal_pending(current)) {
+ range_unlock(tree, lock);
+ rc = -EINTR;
+ goto out;
+ }
+ spin_lock(&tree->rlt_lock);
+ }
+ spin_unlock(&tree->rlt_lock);
+out:
+ return rc;
+}
diff --git a/drivers/staging/lustre/lustre/llite/range_lock.h b/drivers/staging/lustre/lustre/llite/range_lock.h
new file mode 100644
index 0000000..c6d04a6
--- /dev/null
+++ b/drivers/staging/lustre/lustre/llite/range_lock.h
@@ -0,0 +1,82 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * 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 version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.gnu.org/licenses/gpl-2.0.html
+ *
+ * GPL HEADER END
+ */
+/*
+ * Range lock is used to allow multiple threads writing a single shared
+ * file given each thread is writing to a non-overlapping portion of the
+ * file.
+ *
+ * Refer to the possible upstream kernel version of range lock by
+ * Jan Kara <jack@xxxxxxx>: https://lkml.org/lkml/2013/1/31/480
+ *
+ * This file could later replaced by the upstream kernel version.
+ */
+/*
+ * Author: Prakash Surya <surya1@xxxxxxxx>
+ * Author: Bobi Jam <bobijam.xu@xxxxxxxxx>
+ */
+#ifndef _RANGE_LOCK_H
+#define _RANGE_LOCK_H
+
+#include "../../include/linux/libcfs/libcfs.h"
+#include "../include/interval_tree.h"
+
+struct range_lock {
+ struct interval_node rl_node;
+ /**
+ * Process to enqueue this lock.
+ */
+ struct task_struct *rl_task;
+ /**
+ * List of locks with the same range.
+ */
+ struct list_head rl_next_lock;
+ /**
+ * Number of locks in the list rl_next_lock
+ */
+ unsigned int rl_lock_count;
+ /**
+ * Number of ranges which are blocking acquisition of the lock
+ */
+ unsigned int rl_blocking_ranges;
+ /**
+ * Sequence number of range lock. This number is used to get to know
+ * the order the locks are queued; this is required for range_cancel().
+ */
+ __u64 rl_sequence;
+};
+
+static inline struct range_lock *node2rangelock(const struct interval_node *n)
+{
+ return container_of(n, struct range_lock, rl_node);
+}
+
+struct range_lock_tree {
+ struct interval_node *rlt_root;
+ spinlock_t rlt_lock; /* protect range lock tree */
+ __u64 rlt_sequence;
+};
+
+void range_lock_tree_init(struct range_lock_tree *tree);
+void range_lock_init(struct range_lock *lock, __u64 start, __u64 end);
+int range_lock(struct range_lock_tree *tree, struct range_lock *lock);
+void range_unlock(struct range_lock_tree *tree, struct range_lock *lock);
+#endif
--
1.7.1