Re: scsi optimal_io_size changed from 0 on kernel 6.6, to 16773120(32760*512, 4095*4096) on kernel 6.12/6.16

[Wang Yugui <wangyugui@e16-tech.com>]

Hi,

> 
> Wang,
> 
> > scsi optimal_io_size changed from 0 on kernel 6.6, to
> > 16773120(32760*512, 4095*4096) on kernel 6.12/6.16
> 
> Peculiar value. Please share the output of:

It seems the valule of 
	'shost->opt_sectors'
	'dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT'
that means the optimal_io_size of scsi host(hba).

> 
> # sg_readcap -l /dev/sdN
> 
> and
> 
> # sg_vpd -p bl /dev/sdN
> 

# lsscsi
[0:0:0:0]    disk    HITACHI  HUSMH842 CLAR100 C292  /dev/sda
[0:0:1:0]    disk    ATA      INTEL SSDSC2BB48 0121  /dev/sdb
[5:0:0:0]    cd/dvd  PLDS     DVD-ROM DS-8D9SH UD11  /dev/sr0
# sg_readcap -l /dev/sda
Read Capacity results:
   Protection: prot_en=1, p_type=1, p_i_exponent=0 [type 2 protection]
   Logical block provisioning: lbpme=1, lbprz=1
   Last LBA=195371567 (0xba5222f), Number of logical blocks=195371568
   Logical block length=512 bytes
   Logical blocks per physical block exponent=3 [so physical block length=4096 bytes]
   Lowest aligned LBA=0
Hence:
   Device size: 100030242816 bytes, 95396.3 MiB, 100.03 GB
# sg_readcap -l /dev/sda
Read Capacity results:
   Protection: prot_en=1, p_type=1, p_i_exponent=0 [type 2 protection]
   Logical block provisioning: lbpme=1, lbprz=1
   Last LBA=195371567 (0xba5222f), Number of logical blocks=195371568
   Logical block length=512 bytes
   Logical blocks per physical block exponent=3 [so physical block length=4096 bytes]
   Lowest aligned LBA=0
Hence:
   Device size: 100030242816 bytes, 95396.3 MiB, 100.03 GB
#


Best Regards
Wang Yugui (wangyugui@e16-tech.com)
2025/06/25