[lvm-devel] [PATCH 2/5] Add devices/data_alignment_detection to lvm.conf.
Mike Snitzer
snitzer at redhat.com
Thu Jul 30 23:07:16 UTC 2009
Adds 'data_alignment_detection' config option to the devices section of
lvm.conf. If your kernel provides topology information in sysfs (linux
>= 2.6.31) for the Physical Volume, the start of data area will be
aligned on a multiple of the ’minimum_io_size’ or ’optimal_io_size’
exposed in sysfs.
minimum_io_size is used if optimal_io_size is undefined (0). If both
md_chunk_alignment and data_alignment_detection are enabled the result
of data_alignment_detection is used.
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
WHATS_NEW | 1 +
doc/example.conf | 12 ++++++-
lib/config/defaults.h | 1 +
lib/device/device.c | 75 +++++++++++++++++++++++++++++++++++++++++++---
lib/device/device.h | 6 ++++
lib/metadata/metadata.c | 19 ++++++++++++
man/lvm.conf.5.in | 13 +++++++-
7 files changed, 118 insertions(+), 9 deletions(-)
diff --git a/WHATS_NEW b/WHATS_NEW
index 8709a3a..55d2df5 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
Version 2.02.51 -
================================
+ Add devices/data_alignment_detection to lvm.conf.
Add devices/data_alignment_offset_detection to lvm.conf.
Add --dataalignmentoffset to pvcreate to shift start of aligned data area.
Fix _mda_setup() to not check first mda's size before pe_align rounding.
diff --git a/doc/example.conf b/doc/example.conf
index f8528fd..7512b24 100644
--- a/doc/example.conf
+++ b/doc/example.conf
@@ -98,9 +98,17 @@ devices {
# 1 enables; 0 disables.
md_chunk_alignment = 1
+ # By default, the start of a PV's data area will be aligned with
+ # the 'minimum_io_size' or 'optimal_io_size' exposed in sysfs.
+ # minimum_io_size is used if optimal_io_size is undefined (0).
+ # If md_chunk_alignment is enabled, that detects the optimal_io_size.
+ # This setting takes precedence over md_chunk_alignment.
+ # 1 enables; 0 disables.
+ data_alignment_detection = 1
+
# Alignment (in KB) of start of data area when creating a new PV.
- # If a PV is placed directly upon an md device and md_chunk_alignment is
- # enabled this parameter is ignored.
+ # If a PV is placed directly upon an md device and md_chunk_alignment or
+ # data_alignment_detection is enabled this parameter is ignored.
# Set to 0 for the default alignment of 64KB or page size, if larger.
data_alignment = 0
diff --git a/lib/config/defaults.h b/lib/config/defaults.h
index 227ec34..95d8769 100644
--- a/lib/config/defaults.h
+++ b/lib/config/defaults.h
@@ -35,6 +35,7 @@
#define DEFAULT_MD_CHUNK_ALIGNMENT 1
#define DEFAULT_IGNORE_SUSPENDED_DEVICES 1
#define DEFAULT_DATA_ALIGNMENT_OFFSET_DETECTION 1
+#define DEFAULT_DATA_ALIGNMENT_DETECTION 1
#define DEFAULT_LOCK_DIR "/var/lock/lvm"
#define DEFAULT_LOCKING_LIB "liblvm2clusterlock.so"
diff --git a/lib/device/device.c b/lib/device/device.c
index ebd8141..e627517 100644
--- a/lib/device/device.c
+++ b/lib/device/device.c
@@ -285,13 +285,36 @@ int _get_partition_type(struct dev_mgr *dm, struct device *d)
#ifdef linux
+static int _primary_dev(const char *sysfs_dir,
+ struct device *dev, dev_t *result)
+{
+ char path[PATH_MAX+1];
+ struct stat info;
+
+ /* check if dev is a partition */
+ if (dm_snprintf(path, PATH_MAX, "%s/dev/block/%d:%d/partition",
+ sysfs_dir, (int)MAJOR(dev->dev), (int)MINOR(dev->dev)) < 0) {
+ log_error("dm_snprintf partition failed");
+ return 0;
+ }
+
+ if (stat(path, &info) < 0)
+ return 0;
+
+ *result = dev->dev -
+ (MINOR(dev->dev) % max_partitions(MAJOR(dev->dev)));
+ return 1;
+}
+
static unsigned long _dev_topology_attribute(const char *attribute,
const char *sysfs_dir,
struct device *dev)
{
+ const char *sysfs_fmt_str = "%s/dev/block/%d:%d/%s";
char path[PATH_MAX+1], buffer[64];
FILE *fp;
struct stat info;
+ dev_t uninitialized_var(primary);
unsigned long result = 0UL;
if (!attribute || !*attribute)
@@ -300,16 +323,32 @@ static unsigned long _dev_topology_attribute(const char *attribute,
if (!sysfs_dir || !*sysfs_dir)
return_0;
- if (dm_snprintf(path, PATH_MAX, "%s/dev/block/%d:%d/%s",
- sysfs_dir, (int)MAJOR(dev->dev), (int)MINOR(dev->dev),
+ if (dm_snprintf(path, PATH_MAX, sysfs_fmt_str, sysfs_dir,
+ (int)MAJOR(dev->dev), (int)MINOR(dev->dev),
attribute) < 0) {
log_error("dm_snprintf %s failed", attribute);
return 0;
}
- /* check if the desired sysfs attribute exists */
- if (stat(path, &info) < 0)
- return 0;
+ /*
+ * check if the desired sysfs attribute exists
+ * - if not: either the kernel doesn't have topology support
+ * or the device could be a partition
+ */
+ if (stat(path, &info) < 0) {
+ if (!_primary_dev(sysfs_dir, dev, &primary))
+ return 0;
+
+ /* get attribute from partition's primary device */
+ if (dm_snprintf(path, PATH_MAX, sysfs_fmt_str, sysfs_dir,
+ (int)MAJOR(primary), (int)MINOR(primary),
+ attribute) < 0) {
+ log_error("pri dm_snprintf %s failed", attribute);
+ return 0;
+ }
+ if (stat(path, &info) < 0)
+ return 0;
+ }
if (!(fp = fopen(path, "r"))) {
log_sys_error("fopen", path);
@@ -344,6 +383,20 @@ unsigned long dev_alignment_offset(const char *sysfs_dir,
sysfs_dir, dev);
}
+unsigned long dev_minimum_io_size(const char *sysfs_dir,
+ struct device *dev)
+{
+ return _dev_topology_attribute("queue/minimum_io_size",
+ sysfs_dir, dev);
+}
+
+unsigned long dev_optimal_io_size(const char *sysfs_dir,
+ struct device *dev)
+{
+ return _dev_topology_attribute("queue/optimal_io_size",
+ sysfs_dir, dev);
+}
+
#else
unsigned long dev_alignment_offset(const char *sysfs_dir,
@@ -352,4 +405,16 @@ unsigned long dev_alignment_offset(const char *sysfs_dir,
return 0UL;
}
+unsigned long dev_minimum_io_size(const char *sysfs_dir,
+ struct device *dev)
+{
+ return 0UL;
+}
+
+unsigned long dev_optimal_io_size(const char *sysfs_dir,
+ struct device *dev)
+{
+ return 0UL;
+}
+
#endif
diff --git a/lib/device/device.h b/lib/device/device.h
index 32aee41..454fd0b 100644
--- a/lib/device/device.h
+++ b/lib/device/device.h
@@ -103,4 +103,10 @@ int is_partitioned_dev(struct device *dev);
unsigned long dev_alignment_offset(const char *sysfs_dir,
struct device *dev);
+unsigned long dev_minimum_io_size(const char *sysfs_dir,
+ struct device *dev);
+
+unsigned long dev_optimal_io_size(const char *sysfs_dir,
+ struct device *dev);
+
#endif
diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index d050b6c..a3d64a1 100644
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -86,6 +86,25 @@ unsigned long set_pe_align(struct physical_volume *pv, unsigned long data_alignm
dev_md_stripe_width(pv->fmt->cmd->sysfs_dir,
pv->dev));
+ /*
+ * Align to topology's minimum_io_size or optimal_io_size if present
+ * - minimum_io_size - the smallest request the device can perform
+ * w/o incurring a read-modify-write penalty (e.g. MD's chunk size)
+ * - optimal_io_size - the device's preferred unit of receiving I/O
+ * (e.g. MD's stripe width)
+ */
+ if (find_config_tree_bool(pv->fmt->cmd,
+ "devices/data_alignment_detection",
+ DEFAULT_DATA_ALIGNMENT_DETECTION)) {
+ pv->pe_align = MAX(pv->pe_align,
+ dev_minimum_io_size(pv->fmt->cmd->sysfs_dir,
+ pv->dev));
+
+ pv->pe_align = MAX(pv->pe_align,
+ dev_optimal_io_size(pv->fmt->cmd->sysfs_dir,
+ pv->dev));
+ }
+
log_very_verbose("%s: Setting PE alignment to %lu sectors.",
dev_name(pv->dev), pv->pe_align);
diff --git a/man/lvm.conf.5.in b/man/lvm.conf.5.in
index 7b3ee22..82f51ec 100644
--- a/man/lvm.conf.5.in
+++ b/man/lvm.conf.5.in
@@ -137,11 +137,20 @@ has been reused without wiping the md superblocks first.
directly upon an md device, LVM2 will align its data blocks with the
md device's stripe-width.
.IP
+\fBdata_alignment_detection\fP \(em If set to 1, and your kernel provides
+topology information in sysfs for the Physical Volume, the start of data
+area will be aligned on a multiple of the ’minimum_io_size’ or
+’optimal_io_size’ exposed in sysfs. minimum_io_size is used if
+optimal_io_size is undefined (0). If both \fBmd_chunk_alignment\fP and
+\fBdata_alignment_detection\fP are enabled the result of
+\fBdata_alignment_detection\fP is used.
+.IP
\fBdata_alignment\fP \(em Default alignment (in KB) of start of data area
when creating a new Physical Volume using the \fBlvm2\fP format.
If a Physical Volume is placed directly upon an md device and
-\fBmd_chunk_alignment\fP is enabled this parameter is ignored.
-Set to 0 to use the default alignment of 64KB or the page size, if larger.
+\fBmd_chunk_alignment\fP or \fBdata_alignment_detection\fP is enabled
+this parameter is ignored. Set to 0 to use the default alignment of
+64KB or the page size, if larger.
.IP
\fBdata_alignment_offset_detection\fP \(em If set to 1, and your kernel
provides topology information in sysfs for the Physical Volume, the
--
1.6.2.5
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