Re: [PATCH v4 01/10] block: Introduce queue limits for copy-offload support

Damien Le Moal
2022-04-27T12:49:35Z

On 4/26/22 19:12, Nitesh Shetty wrote:
> Add device limits as sysfs entries,
> - copy_offload (RW)
> - copy_max_bytes (RW)
> - copy_max_hw_bytes (RO)
> - copy_max_range_bytes (RW)
> - copy_max_range_hw_bytes (RO)
> - copy_max_nr_ranges (RW)
> - copy_max_nr_ranges_hw (RO)
>
> Above limits help to split the copy payload in block layer.
> copy_offload, used for setting copy offload(1) or emulation(0).
> copy_max_bytes: maximum total length of copy in single payload.
> copy_max_range_bytes: maximum length in a single entry.
> copy_max_nr_ranges: maximum number of entries in a payload.
> copy_max_*_hw_*: Reflects the device supported maximum limits.
>
> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
> Signed-off-by: Arnav Dawn <arnav.dawn@samsung.com>
> ---
> Documentation/ABI/stable/sysfs-block | 83 ++++++++++++++++
> block/blk-settings.c | 59 ++++++++++++
> block/blk-sysfs.c | 138 +++++++++++++++++++++++++++
> include/linux/blkdev.h | 13 +++
> 4 files changed, 293 insertions(+)
>
> diff --git a/Documentation/ABI/stable/sysfs-block b/Documentation/ABI/stable/sysfs-block
> index e8797cd09aff..65e64b5a0105 100644
> --- a/Documentation/ABI/stable/sysfs-block
> +++ b/Documentation/ABI/stable/sysfs-block
> @@ -155,6 +155,89 @@ Description:
> last zone of the device which may be smaller.
>
>
> +What: /sys/block/<disk>/queue/copy_offload
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RW] When read, this file shows whether offloading copy to
> + device is enabled (1) or disabled (0). Writing '0' to this
> + file will disable offloading copies for this device.
> + Writing any '1' value will enable this feature.
> +
> +
> +What: /sys/block/<disk>/queue/copy_max_bytes
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RW] While 'copy_max_hw_bytes' is the hardware limit for the
> + device, 'copy_max_bytes' setting is the software limit.
> + Setting this value lower will make Linux issue smaller size
> + copies.
> +
> +
> +What: /sys/block/<disk>/queue/copy_max_hw_bytes
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RO] Devices that support offloading copy functionality may have
> + internal limits on the number of bytes that can be offloaded
> + in a single operation. The `copy_max_hw_bytes`
> + parameter is set by the device driver to the maximum number of
> + bytes that can be copied in a single operation. Copy
> + requests issued to the device must not exceed this limit.
> + A value of 0 means that the device does not
> + support copy offload.
> +
> +
> +What: /sys/block/<disk>/queue/copy_max_nr_ranges
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RW] While 'copy_max_nr_ranges_hw' is the hardware limit for the
> + device, 'copy_max_nr_ranges' setting is the software limit.
> +
> +
> +What: /sys/block/<disk>/queue/copy_max_nr_ranges_hw
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RO] Devices that support offloading copy functionality may have
> + internal limits on the number of ranges in single copy operation
> + that can be offloaded in a single operation.
> + A range is tuple of source, destination and length of data
> + to be copied. The `copy_max_nr_ranges_hw` parameter is set by
> + the device driver to the maximum number of ranges that can be
> + copied in a single operation. Copy requests issued to the device
> + must not exceed this limit. A value of 0 means that the device
> + does not support copy offload.
> +
> +
> +What: /sys/block/<disk>/queue/copy_max_range_bytes
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RW] While 'copy_max_range_hw_bytes' is the hardware limit for
> + the device, 'copy_max_range_bytes' setting is the software
> + limit.
> +
> +
> +What: /sys/block/<disk>/queue/copy_max_range_hw_bytes
> +Date: April 2022
> +Contact: linux-block@vger.kernel.org
> +Description:
> + [RO] Devices that support offloading copy functionality may have
> + internal limits on the size of data, that can be copied in a
> + single range within a single copy operation.
> + A range is tuple of source, destination and length of data to be
> + copied. The `copy_max_range_hw_bytes` parameter is set by the
> + device driver to set the maximum length in bytes of a range
> + that can be copied in an operation.
> + Copy requests issued to the device must not exceed this limit.
> + Sum of sizes of all ranges in a single opeartion should not
> + exceed 'copy_max_hw_bytes'. A value of 0 means that the device
> + does not support copy offload.
> +
> +
> What: /sys/block/<disk>/queue/crypto/
> Date: February 2022
> Contact: linux-block@vger.kernel.org
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 6ccceb421ed2..70167aee3bf7 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -57,6 +57,12 @@ void blk_set_default_limits(struct queue_limits *lim)
> lim->misaligned = 0;
> lim->zoned = BLK_ZONED_NONE;
> lim->zone_write_granularity = 0;
> + lim->max_hw_copy_sectors = 0;

For readability, I would keep "hw" next to sectors/nr_ranges:

max_copy_hw_sectors
max_copy_sectors
max_copy_hw_nr_ranges
max_copy_nr_ranges
max_copy_range_hw_sectors
max_copy_range_sectors

> + lim->max_copy_sectors = 0;
> + lim->max_hw_copy_nr_ranges = 0;
> + lim->max_copy_nr_ranges = 0;
> + lim->max_hw_copy_range_sectors = 0;
> + lim->max_copy_range_sectors = 0;
> }
> EXPORT_SYMBOL(blk_set_default_limits);
>
> @@ -81,6 +87,12 @@ void blk_set_stacking_limits(struct queue_limits *lim)
> lim->max_dev_sectors = UINT_MAX;
> lim->max_write_zeroes_sectors = UINT_MAX;
> lim->max_zone_append_sectors = UINT_MAX;
> + lim->max_hw_copy_sectors = ULONG_MAX;
> + lim->max_copy_sectors = ULONG_MAX;
> + lim->max_hw_copy_range_sectors = UINT_MAX;
> + lim->max_copy_range_sectors = UINT_MAX;
> + lim->max_hw_copy_nr_ranges = USHRT_MAX;
> + lim->max_copy_nr_ranges = USHRT_MAX;
> }
> EXPORT_SYMBOL(blk_set_stacking_limits);
>
> @@ -177,6 +189,45 @@ void blk_queue_max_discard_sectors(struct request_queue *q,
> }
> EXPORT_SYMBOL(blk_queue_max_discard_sectors);
>
> +/**
> + * blk_queue_max_copy_sectors - set max sectors for a single copy payload
> + * @q: the request queue for the device
> + * @max_copy_sectors: maximum number of sectors to copy
> + **/
> +void blk_queue_max_copy_sectors(struct request_queue *q,

This should be blk_queue_max_copy_hw_sectors().

> + unsigned int max_copy_sectors)
> +{
> + q->limits.max_hw_copy_sectors = max_copy_sectors;
> + q->limits.max_copy_sectors = max_copy_sectors;
> +}
> +EXPORT_SYMBOL_GPL(blk_queue_max_copy_sectors);
> +
> +/**
> + * blk_queue_max_copy_range_sectors - set max sectors for a single range, in a copy payload
> + * @q: the request queue for the device
> + * @max_copy_range_sectors: maximum number of sectors to copy in a single range
> + **/
> +void blk_queue_max_copy_range_sectors(struct request_queue *q,

And this should be blk_queue_max_copy_range_hw_sectors(). Etc for the
other ones below.

> + unsigned int max_copy_range_sectors)
> +{
> + q->limits.max_hw_copy_range_sectors = max_copy_range_sectors;
> + q->limits.max_copy_range_sectors = max_copy_range_sectors;
> +}
> +EXPORT_SYMBOL_GPL(blk_queue_max_copy_range_sectors);
> +
> +/**
> + * blk_queue_max_copy_nr_ranges - set max number of ranges, in a copy payload
> + * @q: the request queue for the device
> + * @max_copy_nr_ranges: maximum number of ranges
> + **/
> +void blk_queue_max_copy_nr_ranges(struct request_queue *q,
> + unsigned int max_copy_nr_ranges)
> +{
> + q->limits.max_hw_copy_nr_ranges = max_copy_nr_ranges;
> + q->limits.max_copy_nr_ranges = max_copy_nr_ranges;
> +}
> +EXPORT_SYMBOL_GPL(blk_queue_max_copy_nr_ranges);
> +
> /**
> * blk_queue_max_secure_erase_sectors - set max sectors for a secure erase
> * @q: the request queue for the device
> @@ -572,6 +623,14 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
> t->max_segment_size = min_not_zero(t->max_segment_size,
> b->max_segment_size);
>
> + t->max_copy_sectors = min(t->max_copy_sectors, b->max_copy_sectors);
> + t->max_hw_copy_sectors = min(t->max_hw_copy_sectors, b->max_hw_copy_sectors);
> + t->max_copy_range_sectors = min(t->max_copy_range_sectors, b->max_copy_range_sectors);
> + t->max_hw_copy_range_sectors = min(t->max_hw_copy_range_sectors,
> + b->max_hw_copy_range_sectors);
> + t->max_copy_nr_ranges = min(t->max_copy_nr_ranges, b->max_copy_nr_ranges);
> + t->max_hw_copy_nr_ranges = min(t->max_hw_copy_nr_ranges, b->max_hw_copy_nr_ranges);
> +
> t->misaligned |= b->misaligned;
>
> alignment = queue_limit_alignment_offset(b, start);
> diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
> index 88bd41d4cb59..bae987c10f7f 100644
> --- a/block/blk-sysfs.c
> +++ b/block/blk-sysfs.c
> @@ -212,6 +212,129 @@ static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *pag
> return queue_var_show(0, page);
> }
>
> +static ssize_t queue_copy_offload_show(struct request_queue *q, char *page)
> +{
> + return queue_var_show(blk_queue_copy(q), page);
> +}
> +
> +static ssize_t queue_copy_offload_store(struct request_queue *q,
> + const char *page, size_t count)
> +{
> + unsigned long copy_offload;
> + ssize_t ret = queue_var_store(&copy_offload, page, count);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (copy_offload && !q->limits.max_hw_copy_sectors)
> + return -EINVAL;
> +
> + if (copy_offload)
> + blk_queue_flag_set(QUEUE_FLAG_COPY, q);
> + else
> + blk_queue_flag_clear(QUEUE_FLAG_COPY, q);
> +
> + return ret;
> +}
> +
> +static ssize_t queue_copy_max_hw_show(struct request_queue *q, char *page)
> +{
> + return sprintf(page, "%llu\n",
> + (unsigned long long)q->limits.max_hw_copy_sectors << 9);
> +}
> +
> +static ssize_t queue_copy_max_show(struct request_queue *q, char *page> +{
> + return sprintf(page, "%llu\n",
> + (unsigned long long)q->limits.max_copy_sectors << 9);
> +}
> +
> +static ssize_t queue_copy_max_store(struct request_queue *q,
> + const char *page, size_t count)
> +{
> + unsigned long max_copy;
> + ssize_t ret = queue_var_store(&max_copy, page, count);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (max_copy & (queue_logical_block_size(q) - 1))
> + return -EINVAL;
> +
> + max_copy >>= 9;
> + if (max_copy > q->limits.max_hw_copy_sectors)
> + max_copy = q->limits.max_hw_copy_sectors;
> +
> + q->limits.max_copy_sectors = max_copy;
> + return ret;
> +}
> +
> +static ssize_t queue_copy_range_max_hw_show(struct request_queue *q, char *page)
> +{
> + return sprintf(page, "%llu\n",
> + (unsigned long long)q->limits.max_hw_copy_range_sectors << 9);
> +}
> +
> +static ssize_t queue_copy_range_max_show(struct request_queue *q,
> + char *page)
> +{
> + return sprintf(page, "%llu\n",
> + (unsigned long long)q->limits.max_copy_range_sectors << 9);
> +}
> +
> +static ssize_t queue_copy_range_max_store(struct request_queue *q,
> + const char *page, size_t count)
> +{
> + unsigned long max_copy;
> + ssize_t ret = queue_var_store(&max_copy, page, count);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (max_copy & (queue_logical_block_size(q) - 1))
> + return -EINVAL;
> +
> + max_copy >>= 9;
> + if (max_copy > UINT_MAX)

On 32-bits arch, unsigned long and unsigned int are the same so this test
is useless for these arch. Better have max_copy declared as unsigned long
long.

> + return -EINVAL;
> +
> + if (max_copy > q->limits.max_hw_copy_range_sectors)
> + max_copy = q->limits.max_hw_copy_range_sectors;
> +
> + q->limits.max_copy_range_sectors = max_copy;
> + return ret;
> +}
> +
> +static ssize_t queue_copy_nr_ranges_max_hw_show(struct request_queue *q, char *page)
> +{
> + return queue_var_show(q->limits.max_hw_copy_nr_ranges, page);
> +}
> +
> +static ssize_t queue_copy_nr_ranges_max_show(struct request_queue *q,
> + char *page)
> +{
> + return queue_var_show(q->limits.max_copy_nr_ranges, page);
> +}
> +
> +static ssize_t queue_copy_nr_ranges_max_store(struct request_queue *q,
> + const char *page, size_t count)
> +{
> + unsigned long max_nr;
> + ssize_t ret = queue_var_store(&max_nr, page, count);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (max_nr > USHRT_MAX)
> + return -EINVAL;
> +
> + if (max_nr > q->limits.max_hw_copy_nr_ranges)
> + max_nr = q->limits.max_hw_copy_nr_ranges;
> +
> + q->limits.max_copy_nr_ranges = max_nr;
> + return ret;
> +}
> +
> static ssize_t queue_write_same_max_show(struct request_queue *q, char *page)
> {
> return queue_var_show(0, page);
> @@ -596,6 +719,14 @@ QUEUE_RO_ENTRY(queue_nr_zones, "nr_zones");
> QUEUE_RO_ENTRY(queue_max_open_zones, "max_open_zones");
> QUEUE_RO_ENTRY(queue_max_active_zones, "max_active_zones");
>
> +QUEUE_RW_ENTRY(queue_copy_offload, "copy_offload");
> +QUEUE_RO_ENTRY(queue_copy_max_hw, "copy_max_hw_bytes");
> +QUEUE_RW_ENTRY(queue_copy_max, "copy_max_bytes");
> +QUEUE_RO_ENTRY(queue_copy_range_max_hw, "copy_max_range_hw_bytes");
> +QUEUE_RW_ENTRY(queue_copy_range_max, "copy_max_range_bytes");
> +QUEUE_RO_ENTRY(queue_copy_nr_ranges_max_hw, "copy_max_nr_ranges_hw");
> +QUEUE_RW_ENTRY(queue_copy_nr_ranges_max, "copy_max_nr_ranges");
> +
> QUEUE_RW_ENTRY(queue_nomerges, "nomerges");
> QUEUE_RW_ENTRY(queue_rq_affinity, "rq_affinity");
> QUEUE_RW_ENTRY(queue_poll, "io_poll");
> @@ -642,6 +773,13 @@ static struct attribute *queue_attrs[] = {
> &queue_discard_max_entry.attr,
> &queue_discard_max_hw_entry.attr,
> &queue_discard_zeroes_data_entry.attr,
> + &queue_copy_offload_entry.attr,
> + &queue_copy_max_hw_entry.attr,
> + &queue_copy_max_entry.attr,
> + &queue_copy_range_max_hw_entry.attr,
> + &queue_copy_range_max_entry.attr,
> + &queue_copy_nr_ranges_max_hw_entry.attr,
> + &queue_copy_nr_ranges_max_entry.attr,
> &queue_write_same_max_entry.attr,
> &queue_write_zeroes_max_entry.attr,
> &queue_zone_append_max_entry.attr,
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 1b24c1fb3bb1..3596fd37fae7 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -270,6 +270,13 @@ struct queue_limits {
> unsigned int discard_alignment;
> unsigned int zone_write_granularity;
>
> + unsigned long max_hw_copy_sectors;
> + unsigned long max_copy_sectors;
> + unsigned int max_hw_copy_range_sectors;
> + unsigned int max_copy_range_sectors;
> + unsigned short max_hw_copy_nr_ranges;
> + unsigned short max_copy_nr_ranges;
> +
> unsigned short max_segments;
> unsigned short max_integrity_segments;
> unsigned short max_discard_segments;
> @@ -574,6 +581,7 @@ struct request_queue {
> #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */
> #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */
> #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */
> +#define QUEUE_FLAG_COPY 30 /* supports copy offload */
>
> #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
> (1 << QUEUE_FLAG_SAME_COMP) | \
> @@ -596,6 +604,7 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q);
> test_bit(QUEUE_FLAG_STABLE_WRITES, &(q)->queue_flags)
> #define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags)
> #define blk_queue_add_random(q) test_bit(QUEUE_FLAG_ADD_RANDOM, &(q)->queue_flags)
> +#define blk_queue_copy(q) test_bit(QUEUE_FLAG_COPY, &(q)->queue_flags)
> #define blk_queue_zone_resetall(q) \
> test_bit(QUEUE_FLAG_ZONE_RESETALL, &(q)->queue_flags)
> #define blk_queue_dax(q) test_bit(QUEUE_FLAG_DAX, &(q)->queue_flags)
> @@ -960,6 +969,10 @@ extern void blk_queue_chunk_sectors(struct request_queue *, unsigned int);
> extern void blk_queue_max_segments(struct request_queue *, unsigned short);
> extern void blk_queue_max_discard_segments(struct request_queue *,
> unsigned short);
> +extern void blk_queue_max_copy_sectors(struct request_queue *q, unsigned int max_copy_sectors);
> +extern void blk_queue_max_copy_range_sectors(struct request_queue *q,
> + unsigned int max_copy_range_sectors);
> +extern void blk_queue_max_copy_nr_ranges(struct request_queue *q, unsigned int max_copy_nr_ranges);
> void blk_queue_max_secure_erase_sectors(struct request_queue *q,
> unsigned int max_sectors);
> extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);

--
Damien Le Moal
Western Digital Research