Hyprocritor

Hi, meet a wireed performance issue, I am using the ISCSI target plugin and trying to expose a zvol to windows. The connection between my nas and windows is a 40Gb/s network card. The ZFS pool is built by 8 HDDs with RAIDZ2 and no performance issue occurs while coping data between windows and this ZFS pool via smb (around 500~700mb/s). The problem is that writing speed drops to 0 or a very low speed after a few seconds with full speed, even through for a large single file, and I noticed that there will be a SINGLLE CPU core will have full usage while others remain 0% usage. Here is my ISCSI configuration: o- / ......................................................................................................................... [...] o- backstores .............................................................................................................. [...] | o- block .................................................................................................. [Storage Objects: 1] | | o- main:new_expansion .......................................... [/dev/zvol/main/new_expansion (10.0TiB) write-thru activated] | | o- alua ................................................................................................... [ALUA Groups: 1] | | o- default_tg_pt_gp ....................................................................... [ALUA state: Active/optimized] | o- fileio ................................................................................................. [Storage Objects: 0] | o- pscsi .................................................................................................. [Storage Objects: 0] | o- ramdisk ................................................................................................ [Storage Objects: 0] o- iscsi ............................................................................................................ [Targets: 1] | o- iqn.2003-01.org.linux-iscsi.tower.x8664:sn.9cc9a9dacbf0 ........................................................... [TPGs: 1] | o- tpg1 ............................................................................................... [no-gen-acls, no-auth] | o- acls .......................................................................................................... [ACLs: 1] | | o- iqn.1991-05.com.microsoft:zhikai-pc .................................................................. [Mapped LUNs: 1] | | o- mapped_lun0 .................................................................... [lun0 block/main:new_expansion (rw)] | o- luns .......................................................................................................... [LUNs: 1] | | o- lun0 ..................................... [block/main:new_expansion (/dev/zvol/main/new_expansion) (default_tg_pt_gp)] | o- portals .................................................................................................... [Portals: 1] | o- 0.0.0.0:3260 ..................................................................................................... [OK] o- loopback ......................................................................................................... [Targets: 0] o- vhost ............................................................................................................ [Targets: 0] o- xen-pvscsi ....................................................................................................... [Targets: 0] Can you help me to figure out how can i fix this issue.