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authorDapeng Mi <dapeng1.mi@linux.intel.com>2026-09-17 09:52:33 +0800
committerIngo Molnar <mingo@kernel.org>2026-09-22 11:37:46 +0200
commit0102c8c7fdfc4bd700971daff2b94470f4eafae4 (patch)
tree531306c2299f9a269f0a986e29f17ba972180104 /Documentation/admin-guide/device-mapper/striped.rst
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perf/x86/intel: Rename DMR offcore_rsp attribute to offmodule_rspgrafted
DMR introduces Offmodule Response events in place of the legacy Offcore Response events, but it still exposes the inherited offcore_rsp PMU attribute for programming the corresponding MSR data. Rename the DMR PMU attribute to offmodule_rsp so the sysfs interface matches the underlying event name and avoids user & tooling confusion. Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://patch.msgid.link/20260917015234.981153-12-dapeng1.mi@linux.intel.com
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+=========
+dm-stripe
+=========
+
+Device-Mapper's "striped" target is used to create a striped (i.e. RAID-0)
+device across one or more underlying devices. Data is written in "chunks",
+with consecutive chunks rotating among the underlying devices. This can
+potentially provide improved I/O throughput by utilizing several physical
+devices in parallel.
+
+Parameters: <num devs> <chunk size> [<dev path> <offset>]+
+ <num devs>:
+ Number of underlying devices.
+ <chunk size>:
+ Size of each chunk of data. Must be at least as
+ large as the system's PAGE_SIZE.
+ <dev path>:
+ Full pathname to the underlying block-device, or a
+ "major:minor" device-number.
+ <offset>:
+ Starting sector within the device.
+
+One or more underlying devices can be specified. The striped device size must
+be a multiple of the chunk size multiplied by the number of underlying devices.
+
+
+Example scripts
+===============
+
+::
+
+ #!/usr/bin/perl -w
+ # Create a striped device across any number of underlying devices. The device
+ # will be called "stripe_dev" and have a chunk-size of 128k.
+
+ my $chunk_size = 128 * 2;
+ my $dev_name = "stripe_dev";
+ my $num_devs = @ARGV;
+ my @devs = @ARGV;
+ my ($min_dev_size, $stripe_dev_size, $i);
+
+ if (!$num_devs) {
+ die("Specify at least one device\n");
+ }
+
+ $min_dev_size = `blockdev --getsz $devs[0]`;
+ for ($i = 1; $i < $num_devs; $i++) {
+ my $this_size = `blockdev --getsz $devs[$i]`;
+ $min_dev_size = ($min_dev_size < $this_size) ?
+ $min_dev_size : $this_size;
+ }
+
+ $stripe_dev_size = $min_dev_size * $num_devs;
+ $stripe_dev_size -= $stripe_dev_size % ($chunk_size * $num_devs);
+
+ $table = "0 $stripe_dev_size striped $num_devs $chunk_size";
+ for ($i = 0; $i < $num_devs; $i++) {
+ $table .= " $devs[$i] 0";
+ }
+
+ `echo $table | dmsetup create $dev_name`;