[dm-devel] [PATCH] dm: add asymmetric stripe target device dirver
Henry Liu
tgvlcw at gmail.com
Tue Dec 26 05:49:11 UTC 2017
No, I don't think so, "target_stripe > stripe" is another condition, but I
do nothing here. If I use "else" the condition "target_strie > stripe" can
not be handled.
2017-12-26 12:22 GMT+08:00 Randy Dunlap <rdunlap at infradead.org>:
> On 12/25/2017 07:52 PM, tgvlcw at gmail.com wrote:
> > From: liuchaowei <tgvlcw at gmail.com>
> >
> > This asymmetric stripe target device driver can achieve better io
> > performance between those devices which possess different io performance
> >
> > There are 2 storage device or flash devices: A and B, their sequential
> > read permance are 220M/s and 315M/s inspectively, so their sequential
>
> performance respectively,
>
> > read speed could be approximately equal to 2:3, if we use stripe type
> > to combine these two devices, their layout could be showed below:
> > --------------------------------------------------------
> > | A1 | A2 | B1 | B2 | B3 |
> > --------------------------------------------------------
> >
> > If we seletect asymmetric stripe type, their layout could be illustrated
>
> select
>
> > follow:
> > --------------------------------------------------------
> > | A1 | B1 |
> > --------------------------------------------------------
> >
> > The former has 5 stripe devices and each stripe device has also equal
> > chunk size, e.g.: 256secs. If there is a data block which size is
> > 1280secs, so transfer the data to this stripe defvice will be split
>
> device
>
> > to 5 ios which io size is 256secs. But if we use the asymmetric
> > stripe device, it only has two stripe devices and each one has be
> > setting in optimal chunk size, e.g.: ratio is 2:3, the first one
> > optimal chunk size is 512secs, the second is 768secs. And same
> > 1280secs data block just only be splited two ios, this can be achieve
>
> split into two ios,
>
> > perfect io performance.
> >
> > Change-Id: Iebaee3480e27022e2b3a7edbfb65425b1166274e
> > Signed-off-by: liuchaowei <tgvlcw at gmail.com>
> > ---
> > Documentation/device-mapper/asymmetric-striped.txt | 85 ++++
> > drivers/md/Kconfig | 11 +
> > drivers/md/Makefile | 1 +
> > drivers/md/dm-asymmetric-stripe.c | 523
> +++++++++++++++++++++
> > drivers/md/dm.c | 5 +
> > include/linux/device-mapper.h | 15 +
> > 6 files changed, 640 insertions(+)
> > create mode 100644 Documentation/device-mapper/asymmetric-striped.txt
> > create mode 100644 drivers/md/dm-asymmetric-stripe.c
> >
> > diff --git a/Documentation/device-mapper/asymmetric-striped.txt
> b/Documentation/device-mapper/asymmetric-striped.txt
> > new file mode 100644
> > index 000000000000..0412a224a49e
> > --- /dev/null
> > +++ b/Documentation/device-mapper/asymmetric-striped.txt
> > @@ -0,0 +1,85 @@
> > +dm-asymmetric-stripe
> > +=========
> > +
> > +Device-Mapper's "asm-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. However, in order to gain maximum I/O performance
> bewteen
>
>
> between
>
> > +slow and fast device, there is a ratio to set up the chunk size among
> these
> > +device.
> > +
> > +Parameters: <num devs> <chunk size> <ratio> [<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.
> > +<ratio>: The proportion of per io size, it is the times as much
> > +as 1 chunk 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. However, there is a ratio can be setting, e.g.: 2:3 means the
> first one
>
> there is a ratio that can be set,
>
> > +striped device optimal width size is 2 time as much as 1 chunk size,
> the second
>
> times
>
> > +striped device is 3.
> > +
> > +
> > +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 $ratio = "2:3";
> > +my $dev_name = "stripe_dev";
> > +my $num_devs = @ARGV;
> > +my @devs = @ARGV;
> > +
> > +if ($num_devs < 2) {
> > +die("Specify at least two devices\n");
> > +}
> > +
> > +
> > +$stripe_average_size = 1073741824
> > +$stripe_dev_size = $stripe_average_size * 5;
> > +
> > +$table = "0 $stripe_dev_size asm-striped $num_devs $chunk_size $ratio";
> > +for ($i = 0; $i < $num_devs; $i++) {
> > +$table .= " $devs[$i] 0";
> > +}
> > +
> > +`echo $table | dmsetup create $dev_name`;
> > +]]
> > +
> > +
> > +Why asymmetric striped
> > +=======================
> > +Considering one case:
> > +There are 2 storage device or flash devices: A and B, their sequential
> > +read permance are 220M/s and 315M/s inspectively, so their sequential
>
> performance respectively,
>
> > +read speed could be approximately equal to 2:3, if we use stripe type
> > +to combine these two devices, their layout could be showed below:
> > +--------------------------------------------------------
> > +| A1 | A2 | B1 | B2 | B3 |
> > +--------------------------------------------------------
> > +
> > +If we seletect asymmetric stripe type, their layout could be illustrated
>
> select
>
> > +follow:
> > +--------------------------------------------------------
> > +| A1 | B1 |
> > +--------------------------------------------------------
> > +
> > +The former has 5 stripe devices and each stripe device has also equal
> > +chunk size, e.g.: 256secs. If there is a data block which size is
> 1280secs,
> > +so transfer the data to this stripe defvice will be split to 5 ios
> which io
>
> device
>
> > +size is 256secs. But if we use the asymmetric stripe device, it only
> has two
> > +stripe devices and each one has be setting in optimal chunk size, e.g.:
> ratio
> > +is 2:3, the first one optimal chunk size is 512secs, the second is
> 768secs.
> > +And same 1280secs data block just only be splited two ios, this can be
> achieve
>
> split into two ios,
>
> > +perfect io performance.
> > +
> > diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> > index 7d5aa2c5c81d..4232b929c2f3 100644
> > --- a/drivers/md/Kconfig
> > +++ b/drivers/md/Kconfig
> > @@ -455,6 +455,17 @@ config DM_FLAKEY
> > ---help---
> > A target that intermittently fails I/O for debugging purposes.
> >
> > +config DM_ASYMMETRIC_STRIPE
> > + tristate "DM asymmetric stripe(asymmetric raid0)"
> > + depends on BLK_DEV_DM
> > + ---help---
> > + This device-mapper target creates a asymmetric raid0/stripe
> device that
> > + support asymmetric stripe chunk size and can gain same
> performance as
> > + raid0 device
>
> Align "support" and "raid0" under "This". And end the sentence with a
> period (".").
>
> > +
> > + You must configure the accurate ratio between different
> physical storage
> > + device respectively
>
> End sentence with a period.
>
> > +
> > config DM_VERITY
> > tristate "Verity target support"
> > depends on BLK_DEV_DM
>
> > diff --git a/drivers/md/dm-asymmetric-stripe.c
> b/drivers/md/dm-asymmetric-stripe.c
> > new file mode 100644
> > index 000000000000..4ef3915b435a
> > --- /dev/null
> > +++ b/drivers/md/dm-asymmetric-stripe.c
> > @@ -0,0 +1,523 @@
> > +/*
> > + * Copyright (C) 2018 Smartisan, Inc.
> > + *
> > + * This software is licensed under the terms of the GNU General Public
> > + * License version 2, as published by the Free Software Foundation, and
> > + * may be copied, distributed, and modified under those terms.
> > + *
> > + * 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.
> > + *
> > + * Author: <tgvlcw at gmail.com>
> > + * Name: Henry Liu
> > + *
> > + */
> > +
> > +
> > +#include "dm.h"
> > +#include <linux/device-mapper.h>
> > +
>
> #include <linux/atomic.h>
>
> > +#include <linux/module.h>
> > +#include <linux/init.h>
>
> #include <linux/kernel.h>
>
> > +#include <linux/blkdev.h>
> > +#include <linux/bio.h>
>
> #include <linux/bitops.h>
>
> > +#include <linux/slab.h>
> > +#include <linux/log2.h>
>
> #include <linux/workqueue.h>
>
> > +
> > +#define DM_MSG_PREFIX "asm-striped"
> > +#define DM_IO_ERROR_THRESHOLD 15
>
> > +/*
> > + * An event is triggered whenever a drive
> > + * drops out of a stripe volume.
> > + */
> > +static void trigger_event(struct work_struct *work)
> > +{
> > + asm_stripe_c *sc = container_of(work, asm_stripe_c, trigger_event);
> > +
> > + dm_table_event(sc->ti->table);
> > +}
> > +
> > + static inline
>
> Above line should not be indented.
> Above and below should be on one line if <= 80 characters.
>
> > +asm_stripe_c *alloc_context(unsigned int stripes)
> > +{
> > + size_t len;
> > +
> > + if (dm_array_too_big(sizeof(asm_stripe_c),
> > + sizeof(asm_stripe),
> > + stripes))
> > + return NULL;
> > +
> > + len = sizeof(asm_stripe_c) + (sizeof(asm_stripe) * stripes);
> > +
> > + return kmalloc(len, GFP_KERNEL);
> > +}
>
> > +static int set_stripe_ratio(struct dm_target *ti,
> > + asm_stripe_c *sc,
> > + char *ratio_str)
> > +{
> > + char *p;
> > + unsigned int i;
> > + uint32_t r = 0, ratio;
> > + char *tmp_ratio = ratio_str;
> > +
> > + if (sizeof(sc->ratio_str) < strlen(ratio_str)) {
> > + ti->error = "Too big stripe ratio string";
> > + return -ENOMEM;
> > + }
> > +
> > + strlcpy(sc->ratio_str, ratio_str, strlen(ratio_str) + 1);
> > + for (i = 0; i < sc->stripes; i++) {
> > + p = strsep(&tmp_ratio, ":");
> > + if (p == NULL)
> > + return -EINVAL;
> > +
> > + if (kstrtouint(p, 10, &ratio) || !ratio)
> > + return -EINVAL;
> > +
> > + sc->stripe[i].ratio = ratio;
> > + r += ratio;
> > + }
> > +
> > + sc->total_ratio = r;
> > + sc->avg_width = ti->len / r;
> > + sc->stripe_size = r * sc->chunk_size;
> > +
> > + return 0;
> > +}
>
> Insert blank line here.
>
> > +/*
> > + * Construct a striped mapping.
> > + * <number of stripes> <chunk size> <ratio> [<dev_path> <offset>]+
> > + */
> > +static int asymmetric_stripe_ctr(struct dm_target *ti,
> > + unsigned int argc,
> > + char **argv)
> > +{
>
> [snip]
>
>
> > +static void asymmetric_stripe_map_range_sector(asm_stripe_c *sc,
> > + sector_t sector,
> > + uint32_t target_stripe,
> > + sector_t *result)
> > +{
> > + sector_t width_offset;
> > + uint32_t stripe;
> > +
> > + width_offset = stripe_index_fetch(sc, §or, &stripe);
> > +
> > + *result = sector * sc->stripe[target_stripe].opt_io_size;
> > +
> > + if (target_stripe < stripe)
> > + *result += sc->stripe[target_stripe].opt_io_size;
> > + else if (target_stripe == stripe)
> > + *result += width_offset;
>
> Here you don't expect target_stripe ever to be > stripe, right?
> Then the last "else if" can just be "else"...
>
>
> > +}
> > +
>
>
> --
> ~Randy
>
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