| Message ID | 1450306433-20166-3-git-send-email-martin.petersen@oracle.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
> -----Original Message----- > From: linux-block-owner@vger.kernel.org [mailto:linux-block- > owner@vger.kernel.org] On Behalf Of Martin K. Petersen > Sent: Wednesday, December 16, 2015 4:54 PM > To: linux-scsi@vger.kernel.org; linux-block@vger.kernel.org > Cc: Martin K. Petersen <martin.petersen@oracle.com> > Subject: [PATCH 3/3] block: Export max_dev_sectors_kb in sysfs > ... > diff --git a/Documentation/block/queue-sysfs.txt ... > @@ -55,9 +55,15 @@ logical_block_size (RO) > ----------------------- > This is the logcal block size of the device, in bytes. Since you're in the vicinity, consider adding an i to logcal. > > +max_dev_sectors_kb (R) > +---------------------- The others use (RO) rather than just (R). > +This is the maximum number of kilobytes supported by the storage > +device for a READ or WRITE request. > + > max_hw_sectors_kb (RO) > ---------------------- > -This is the maximum number of kilobytes supported in a single data transfer. > +This is the maximum number of kilobytes supported by the storage > +controller in a single data transfer. ... > @@ -68,7 +74,8 @@ max_sectors_kb (RW) > ------------------- > This is the maximum number of kilobytes that the block layer will allow > for a filesystem request. Must be smaller than or equal to the maximum > -size allowed by the hardware. > +size allowed by the storage controller (max_hw_sectors_kb) and the > +maximum size allowed by the storage device (max_dev_sectors_kb). Each one uses a different phrase: * for a READ or WRITE request * in a single data transfer * for a filesystem request Is some subtle difference being implied? Since there are existing sysfs file with similar names, you're stuck using _kb for the new one. However, I suggest that the Documentation at least mention these are really KiB, not kilobyte, units. --- Robert Elliott, HPE Persistent Memory -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2015-12-16 at 17:53 -0500, Martin K. Petersen wrote: > Some storage devices report a maximum transfer length which indicates > the maximum size of an I/O request that the device can process. This > limit is enforced in combination with the controller's max_hw_sectors > and DMA constraints to ensure that we do not issue a command too big for > the device. > > Export the max_dev_sectors_kb queue limit in sysfs and update the > documentation accordingly. > > Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> > --- > Documentation/ABI/testing/sysfs-block | 9 +++++++++ > Documentation/block/queue-sysfs.txt | 11 +++++++++-- > block/blk-settings.c | 4 +++- > block/blk-sysfs.c | 13 +++++++++++++ > 4 files changed, 34 insertions(+), 3 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block > index 71d184dbb70d..4f284d38c085 100644 > --- a/Documentation/ABI/testing/sysfs-block > +++ b/Documentation/ABI/testing/sysfs-block > @@ -235,3 +235,12 @@ Description: > write_same_max_bytes is 0, write same is not supported > by the device. > > +What: /sys/block/<disk>/queue/max_dev_sectors_kb > +Date: December 2015 > +Contact: Martin K. Petersen <martin.petersen@oracle.com> > +Description: > + Some storage devices report the maximum size that the > + device can process in a single READ or WRITE > + request. This limit is used in combination with > + constraints set by the controller driver to limit the > + size of filesystem requests. > diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt > index e5d914845be6..a078995f3eae 100644 > --- a/Documentation/block/queue-sysfs.txt > +++ b/Documentation/block/queue-sysfs.txt > @@ -55,9 +55,15 @@ logical_block_size (RO) > ----------------------- > This is the logcal block size of the device, in bytes. > > +max_dev_sectors_kb (R) > +---------------------- > +This is the maximum number of kilobytes supported by the storage device > +for a READ or WRITE request. > + > max_hw_sectors_kb (RO) > ---------------------- > -This is the maximum number of kilobytes supported in a single data transfer. > +This is the maximum number of kilobytes supported by the storage > +controller in a single data transfer. > > max_integrity_segments (RO) > --------------------------- > @@ -68,7 +74,8 @@ max_sectors_kb (RW) > ------------------- > This is the maximum number of kilobytes that the block layer will allow > for a filesystem request. Must be smaller than or equal to the maximum > -size allowed by the hardware. > +size allowed by the storage controller (max_hw_sectors_kb) and the > +maximum size allowed by the storage device (max_dev_sectors_kb). > > max_segments (RO) > ----------------- > diff --git a/block/blk-settings.c b/block/blk-settings.c > index dd4973583978..362b0179c86a 100644 > --- a/block/blk-settings.c > +++ b/block/blk-settings.c > @@ -232,7 +232,9 @@ EXPORT_SYMBOL(blk_queue_bounce_limit); > * max_sectors is a soft limit imposed by the block layer for > * filesystem type requests. This value can be overridden on a > * per-device basis in /sys/block/<device>/queue/max_sectors_kb. > - * The soft limit can not exceed max_hw_sectors. > + * > + * The soft limit's lower bound is the page cache size and it can not > + * exceed neither max_hw_sectors, nor max_dev_sectors. > **/ > void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) > { > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index e140cc487ce1..c289f9f6dcd9 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -225,6 +225,13 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) > return queue_var_show(max_hw_sectors_kb, (page)); > } > > +static ssize_t queue_max_dev_sectors_show(struct request_queue *q, char *page) > +{ > + int max_dev_sectors_kb = q->limits.max_dev_sectors >> 1; Consider adding inline queue_max_dev_sectors() to blkdev.h and using it in the line above? > + > + return queue_var_show(max_dev_sectors_kb, (page)); > +} > + > #define QUEUE_SYSFS_BIT_FNS(name, flag, neg) \ > static ssize_t \ > queue_show_##name(struct request_queue *q, char *page) \ > @@ -371,6 +378,11 @@ static struct queue_sysfs_entry queue_max_hw_sectors_entry = { > .show = queue_max_hw_sectors_show, > }; > > +static struct queue_sysfs_entry queue_max_dev_sectors_entry = { > + .attr = {.name = "max_dev_sectors_kb", .mode = S_IRUGO }, > + .show = queue_max_dev_sectors_show, > +}; > + > static struct queue_sysfs_entry queue_max_segments_entry = { > .attr = {.name = "max_segments", .mode = S_IRUGO }, > .show = queue_max_segments_show, > @@ -483,6 +495,7 @@ static struct attribute *default_attrs[] = { > &queue_requests_entry.attr, > &queue_ra_entry.attr, > &queue_max_hw_sectors_entry.attr, > + &queue_max_dev_sectors_entry.attr, > &queue_max_sectors_entry.attr, > &queue_max_segments_entry.attr, > &queue_max_integrity_segments_entry.attr, Reviewed-by: Ewan D. Milne <emilne@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block index 71d184dbb70d..4f284d38c085 100644 --- a/Documentation/ABI/testing/sysfs-block +++ b/Documentation/ABI/testing/sysfs-block @@ -235,3 +235,12 @@ Description: write_same_max_bytes is 0, write same is not supported by the device. +What: /sys/block/<disk>/queue/max_dev_sectors_kb +Date: December 2015 +Contact: Martin K. Petersen <martin.petersen@oracle.com> +Description: + Some storage devices report the maximum size that the + device can process in a single READ or WRITE + request. This limit is used in combination with + constraints set by the controller driver to limit the + size of filesystem requests. diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt index e5d914845be6..a078995f3eae 100644 --- a/Documentation/block/queue-sysfs.txt +++ b/Documentation/block/queue-sysfs.txt @@ -55,9 +55,15 @@ logical_block_size (RO) ----------------------- This is the logcal block size of the device, in bytes. +max_dev_sectors_kb (R) +---------------------- +This is the maximum number of kilobytes supported by the storage device +for a READ or WRITE request. + max_hw_sectors_kb (RO) ---------------------- -This is the maximum number of kilobytes supported in a single data transfer. +This is the maximum number of kilobytes supported by the storage +controller in a single data transfer. max_integrity_segments (RO) --------------------------- @@ -68,7 +74,8 @@ max_sectors_kb (RW) ------------------- This is the maximum number of kilobytes that the block layer will allow for a filesystem request. Must be smaller than or equal to the maximum -size allowed by the hardware. +size allowed by the storage controller (max_hw_sectors_kb) and the +maximum size allowed by the storage device (max_dev_sectors_kb). max_segments (RO) ----------------- diff --git a/block/blk-settings.c b/block/blk-settings.c index dd4973583978..362b0179c86a 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -232,7 +232,9 @@ EXPORT_SYMBOL(blk_queue_bounce_limit); * max_sectors is a soft limit imposed by the block layer for * filesystem type requests. This value can be overridden on a * per-device basis in /sys/block/<device>/queue/max_sectors_kb. - * The soft limit can not exceed max_hw_sectors. + * + * The soft limit's lower bound is the page cache size and it can not + * exceed neither max_hw_sectors, nor max_dev_sectors. **/ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors) { diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index e140cc487ce1..c289f9f6dcd9 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -225,6 +225,13 @@ static ssize_t queue_max_hw_sectors_show(struct request_queue *q, char *page) return queue_var_show(max_hw_sectors_kb, (page)); } +static ssize_t queue_max_dev_sectors_show(struct request_queue *q, char *page) +{ + int max_dev_sectors_kb = q->limits.max_dev_sectors >> 1; + + return queue_var_show(max_dev_sectors_kb, (page)); +} + #define QUEUE_SYSFS_BIT_FNS(name, flag, neg) \ static ssize_t \ queue_show_##name(struct request_queue *q, char *page) \ @@ -371,6 +378,11 @@ static struct queue_sysfs_entry queue_max_hw_sectors_entry = { .show = queue_max_hw_sectors_show, }; +static struct queue_sysfs_entry queue_max_dev_sectors_entry = { + .attr = {.name = "max_dev_sectors_kb", .mode = S_IRUGO }, + .show = queue_max_dev_sectors_show, +}; + static struct queue_sysfs_entry queue_max_segments_entry = { .attr = {.name = "max_segments", .mode = S_IRUGO }, .show = queue_max_segments_show, @@ -483,6 +495,7 @@ static struct attribute *default_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, &queue_max_hw_sectors_entry.attr, + &queue_max_dev_sectors_entry.attr, &queue_max_sectors_entry.attr, &queue_max_segments_entry.attr, &queue_max_integrity_segments_entry.attr,
Some storage devices report a maximum transfer length which indicates the maximum size of an I/O request that the device can process. This limit is enforced in combination with the controller's max_hw_sectors and DMA constraints to ensure that we do not issue a command too big for the device. Export the max_dev_sectors_kb queue limit in sysfs and update the documentation accordingly. Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> --- Documentation/ABI/testing/sysfs-block | 9 +++++++++ Documentation/block/queue-sysfs.txt | 11 +++++++++-- block/blk-settings.c | 4 +++- block/blk-sysfs.c | 13 +++++++++++++ 4 files changed, 34 insertions(+), 3 deletions(-)