Date: Wed, 9 Sep 2020 17:59:10 +0500 From: "Eugene M. Zheganin" <emz@norma.perm.ru> To: freebsd-stable@freebsd.org Subject: Re: spa_namespace_lock and concurrent zfs commands Message-ID: <0d113463-be6d-5c6b-3cfc-867a0891e7d8@norma.perm.ru> In-Reply-To: <e458ba84-c044-1502-3672-c89e353ef303@norma.perm.ru> References: <e458ba84-c044-1502-3672-c89e353ef303@norma.perm.ru>
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On 09.09.2020 17:29, Eugene M. Zheganin wrote: > Hello, > > I'm using sort of FreeBSD ZFS appliance with custom API, and I'm > suffering from huge timeouts when large (dozens, actually) of > concurrent zfs/zpool commands are issued > (get/create/destroy/snapshot/clone mostly). > > Are there any tunables that could help mitigate this ? > > Once I took part in reporting the > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=203906 , but the > issue that time got resolved somehow. Now I have another set of > FreeBSD SANs and it;'s back. I've read the > https://wiki.freebsd.org/AndriyGapon/AvgZFSLocking and I realize this > probably doesn't have a quick solution, but still... > This actually looks like this (sometime it takes several [dozens of] minutes): root@cg-mr-prod-stg09:/usr/ports/sysutils/smartmontools # zfs get volmode load: 3.58š cmd: zfs 70231 [spa_namespace_lock] 16.38r 0.00u 0.00s 0% 3872k load: 3.58š cmd: zfs 70231 [spa_namespace_lock] 16.59r 0.00u 0.00s 0% 3872k load: 3.58š cmd: zfs 70231 [spa_namespace_lock] 16.76r 0.00u 0.00s 0% 3872k load: 3.58š cmd: zfs 70231 [spa_namespace_lock] 16.90r 0.00u 0.00s 0% 3872k load: 3.58š cmd: zfs 70231 [spa_namespace_lock] 17.04r 0.00u 0.00s 0% 3872k load: 3.58š cmd: zfs 70231 [spa_namespace_lock] 17.17r 0.00u 0.00s 0% 3872k root@cg-mr-prod-stg09:~ # ps ax | grep volmode 70231š 5š D+ššššššš 0:00.00 zfs get volmode 70233š 6š S+ššššššš 0:00.00 grep volmode root@cg-mr-prod-stg09:~ # procstat -kk 70231 š PIDššš TID COMMššššššššššššššš TDNAME KSTACK 70231 101598 zfsšššššššššššššššš - mi_switch+0xe2 sleepq_wait+0x2c _sx_xlock_hard+0x459 spa_all_configs+0x1aa zfs_ioc_pool_configs+0x19 zfsdev_ioctl+0x72e devfs_ioctl+0xad VOP_IOCTL_APV+0x7c vn_ioctl+0x16a devfs_ioctl_f+0x1f kern_ioctl+0x2be sys_ioctl+0x15d amd64_syscall+0x364 fast_syscall_common+0x101 root@cg-mr-prod-stg09:~ # Thanks. Eugene.
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