| Message ID | 20181012023012.29923-3-damien.lemoal@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Zoned block device support improvements | expand |
On 10/12/18 4:30 AM, Damien Le Moal wrote: > Handling checks of ZBC device capacity using the max_lba field of the > REPORT ZONES command reply for disks with rc_basis == 0 can be done > using the same report zones command reply used to check the "same" > field. > > Avoid executing a report zones command solely to check the disk capacity > by merging sd_zbc_check_capacity() into sd_zbc_check_zone_size() and > renaming that function to sd_zbc_check_zones(). This removes a costly > execution of a full report zones command and so reduces device scan > duration at boot time as well as the duration of disk revalidate calls. > > Furthermore, setting the partial report bit in the REPORT ZONES command > cdb can significantly reduce this command execution time as the device > does not have to count and report the total number of zones that could > be reported assuming a large enough reply buffer. A non-partial zone > report is necessary only for the first execution of report zones used to > check the same field value (to ensure that this value applies to all > zones of the disk). All other calls to sd_zbc_report_zones() can use a > partial report to reduce execution time. > > Using a 14 TB ZBC disk, these simple changes reduce device scan time at > boot from about 3.5s down to about 900ms. Disk revalidate times are also > reduced from about 450ms down to 230ms. > > Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> > Reviewed-by: Christoph Hellwig <hch@lst.de> > --- > drivers/scsi/sd_zbc.c | 94 ++++++++++++++++++------------------------- > 1 file changed, 40 insertions(+), 54 deletions(-) > Reviewed-by: Hannes Reinecke <hare@suse.com> ... and it'll be your fault if there are drives which do not support the 'partial' bit :) Cheers, Hannes
On 2018/10/12 16:33, Hannes Reinecke wrote: > On 10/12/18 4:30 AM, Damien Le Moal wrote: >> Handling checks of ZBC device capacity using the max_lba field of the >> REPORT ZONES command reply for disks with rc_basis == 0 can be done >> using the same report zones command reply used to check the "same" >> field. >> >> Avoid executing a report zones command solely to check the disk capacity >> by merging sd_zbc_check_capacity() into sd_zbc_check_zone_size() and >> renaming that function to sd_zbc_check_zones(). This removes a costly >> execution of a full report zones command and so reduces device scan >> duration at boot time as well as the duration of disk revalidate calls. >> >> Furthermore, setting the partial report bit in the REPORT ZONES command >> cdb can significantly reduce this command execution time as the device >> does not have to count and report the total number of zones that could >> be reported assuming a large enough reply buffer. A non-partial zone >> report is necessary only for the first execution of report zones used to >> check the same field value (to ensure that this value applies to all >> zones of the disk). All other calls to sd_zbc_report_zones() can use a >> partial report to reduce execution time. >> >> Using a 14 TB ZBC disk, these simple changes reduce device scan time at >> boot from about 3.5s down to about 900ms. Disk revalidate times are also >> reduced from about 450ms down to 230ms. >> >> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> >> Reviewed-by: Christoph Hellwig <hch@lst.de> >> --- >> drivers/scsi/sd_zbc.c | 94 ++++++++++++++++++------------------------- >> 1 file changed, 40 insertions(+), 54 deletions(-) >> > Reviewed-by: Hannes Reinecke <hare@suse.com> > > ... and it'll be your fault if there are drives which do not support the > 'partial' bit :) The partial bit definition is in the ZBC/ZAC specs and it is not optional. If a drive does not support it, it would be out of specs :) > > Cheers, > > Hannes >
On 10/12/2018 09:33 AM, Hannes Reinecke wrote: > On 10/12/18 4:30 AM, Damien Le Moal wrote: >> Handling checks of ZBC device capacity using the max_lba field of the >> REPORT ZONES command reply for disks with rc_basis == 0 can be done >> using the same report zones command reply used to check the "same" >> field. >> >> Avoid executing a report zones command solely to check the disk capacity >> by merging sd_zbc_check_capacity() into sd_zbc_check_zone_size() and >> renaming that function to sd_zbc_check_zones(). This removes a costly >> execution of a full report zones command and so reduces device scan >> duration at boot time as well as the duration of disk revalidate calls. >> >> Furthermore, setting the partial report bit in the REPORT ZONES command >> cdb can significantly reduce this command execution time as the device >> does not have to count and report the total number of zones that could >> be reported assuming a large enough reply buffer. A non-partial zone >> report is necessary only for the first execution of report zones used to >> check the same field value (to ensure that this value applies to all >> zones of the disk). All other calls to sd_zbc_report_zones() can use a >> partial report to reduce execution time. >> >> Using a 14 TB ZBC disk, these simple changes reduce device scan time at >> boot from about 3.5s down to about 900ms. Disk revalidate times are also >> reduced from about 450ms down to 230ms. >> >> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> >> Reviewed-by: Christoph Hellwig <hch@lst.de> >> --- >> drivers/scsi/sd_zbc.c | 94 ++++++++++++++++++------------------------- >> 1 file changed, 40 insertions(+), 54 deletions(-) >> > Reviewed-by: Hannes Reinecke <hare@suse.com> > > ... and it'll be your fault if there are drives which do not support > the 'partial' bit :) > I already look forward the quirk list ;) > Cheers, > > Hannes
diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c index 0b7d8787f785..ca73c46931c0 100644 --- a/drivers/scsi/sd_zbc.c +++ b/drivers/scsi/sd_zbc.c @@ -67,11 +67,17 @@ static void sd_zbc_parse_report(struct scsi_disk *sdkp, u8 *buf, * @buf: Buffer to use for the reply * @buflen: the buffer size * @lba: Start LBA of the report + * @partial: Do partial report * * For internal use during device validation. + * Using partial=true can significantly speed up execution of a report zones + * command because the disk does not have to count all possible report matching + * zones and will only report the count of zones fitting in the command reply + * buffer. */ static int sd_zbc_report_zones(struct scsi_disk *sdkp, unsigned char *buf, - unsigned int buflen, sector_t lba) + unsigned int buflen, sector_t lba, + bool partial) { struct scsi_device *sdp = sdkp->device; const int timeout = sdp->request_queue->rq_timeout; @@ -85,6 +91,8 @@ static int sd_zbc_report_zones(struct scsi_disk *sdkp, unsigned char *buf, cmd[1] = ZI_REPORT_ZONES; put_unaligned_be64(lba, &cmd[2]); put_unaligned_be32(buflen, &cmd[10]); + if (partial) + cmd[14] = ZBC_REPORT_ZONE_PARTIAL; memset(buf, 0, buflen); result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE, @@ -350,60 +358,25 @@ static int sd_zbc_check_zoned_characteristics(struct scsi_disk *sdkp, return 0; } -/** - * sd_zbc_check_capacity - Check reported capacity. - * @sdkp: Target disk - * @buf: Buffer to use for commands - * - * ZBC drive may report only the capacity of the first conventional zones at - * LBA 0. This is indicated by the RC_BASIS field of the read capacity reply. - * Check this here. If the disk reported only its conventional zones capacity, - * get the total capacity by doing a report zones. - */ -static int sd_zbc_check_capacity(struct scsi_disk *sdkp, unsigned char *buf) -{ - sector_t lba; - int ret; - - if (sdkp->rc_basis != 0) - return 0; - - /* Do a report zone to get the maximum LBA to check capacity */ - ret = sd_zbc_report_zones(sdkp, buf, SD_BUF_SIZE, 0); - if (ret) - return ret; - - /* The max_lba field is the capacity of this device */ - lba = get_unaligned_be64(&buf[8]); - if (lba + 1 == sdkp->capacity) - return 0; - - if (sdkp->first_scan) - sd_printk(KERN_WARNING, sdkp, - "Changing capacity from %llu to max LBA+1 %llu\n", - (unsigned long long)sdkp->capacity, - (unsigned long long)lba + 1); - sdkp->capacity = lba + 1; - - return 0; -} - #define SD_ZBC_BUF_SIZE 131072U /** - * sd_zbc_check_zone_size - Check the device zone sizes + * sd_zbc_check_zones - Check the device capacity and zone sizes * @sdkp: Target disk * - * Check that all zones of the device are equal. The last zone can however - * be smaller. The zone size must also be a power of two number of LBAs. + * Check that the device capacity as reported by READ CAPACITY matches the + * max_lba value (plus one)of the report zones command reply. Also check that + * all zones of the device have an equal size, only allowing the last zone of + * the disk to have a smaller size (runt zone). The zone size must also be a + * power of two. * * Returns the zone size in number of blocks upon success or an error code * upon failure. */ -static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp) +static s64 sd_zbc_check_zones(struct scsi_disk *sdkp) { u64 zone_blocks = 0; - sector_t block = 0; + sector_t max_lba, block = 0; unsigned char *buf; unsigned char *rec; unsigned int buf_len; @@ -416,11 +389,28 @@ static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp) if (!buf) return -ENOMEM; - /* Do a report zone to get the same field */ - ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, 0); + /* Do a report zone to get max_lba and the same field */ + ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, 0, false); if (ret) goto out_free; + if (sdkp->rc_basis == 0) { + /* The max_lba field is the capacity of this device */ + max_lba = get_unaligned_be64(&buf[8]); + if (sdkp->capacity != max_lba + 1) { + if (sdkp->first_scan) + sd_printk(KERN_WARNING, sdkp, + "Changing capacity from %llu to max LBA+1 %llu\n", + (unsigned long long)sdkp->capacity, + (unsigned long long)max_lba + 1); + sdkp->capacity = max_lba + 1; + } + } + + /* + * Check same field: for any value other than 0, we know that all zones + * have the same size. + */ same = buf[4] & 0x0f; if (same > 0) { rec = &buf[64]; @@ -458,7 +448,7 @@ static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp) if (block < sdkp->capacity) { ret = sd_zbc_report_zones(sdkp, buf, - SD_ZBC_BUF_SIZE, block); + SD_ZBC_BUF_SIZE, block, true); if (ret) goto out_free; } @@ -574,7 +564,8 @@ sd_zbc_setup_seq_zones_bitmap(struct scsi_disk *sdkp, u32 zone_shift, goto out; while (lba < sdkp->capacity) { - ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, lba); + ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, + lba, true); if (ret) goto out; lba = sd_zbc_get_seq_zones(sdkp, buf, SD_ZBC_BUF_SIZE, @@ -692,16 +683,11 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf) if (ret) goto err; - /* Check capacity */ - ret = sd_zbc_check_capacity(sdkp, buf); - if (ret) - goto err; - /* * Check zone size: only devices with a constant zone size (except * an eventual last runt zone) that is a power of 2 are supported. */ - zone_blocks = sd_zbc_check_zone_size(sdkp); + zone_blocks = sd_zbc_check_zones(sdkp); ret = -EFBIG; if (zone_blocks != (u32)zone_blocks) goto err;