search for: dirty_expire_centisecs

...ound makes me think that this may be related to queue depth, nr_requests and possibly VM params (the latter from https://bugzilla.redhat.com/show_bug.cgi?id=121434#c275). These are the default settings: /sys/block/sda/device/queue_depth = 254 /sys/block/sda/queue/nr_requests = 8192 /proc/sys/vm/dirty_expire_centisecs = 3000 /proc/sys/vm/dirty_ratio = 30 3Ware mentions elevator=deadline, blockdev --setra 16384 along with nr_requests=512 in their performance tuning doc - these alone seem to make no difference to the latency problem. Setting dirty_expire_centisecs = 1000 and dirty_ratio = 5 does indeed reduce...

...e USB hard disk, I find that the page cache eats up almost about 100MB and occasionally the system runs out of memory. I even tried tweaking the /proc/sys/vm settings with the following values, but it did not help. /proc/sys/vm/dirty_background_ratio = 2 /proc/sys/vm/dirty_ratio = 5 /proc/sys/vm/dirty_expire_centisecs = 1000 /proc/sys/vm/vfs_cache_pressure = 10000 I also tried copying the huge file locally from one folder to another through the USB interface using dd oflag=direct flag (unbuffered write). But the page cache again ate away about 100MB RAM. Has anybody here seen the same problem? Is there a possi...

...ptimise > everything. > > Obviously the exact type of writes is important (lots of small writes written > and flushed vs fewer big unsynced writes), so you'd want to poke it with > iostat to see what kind of writes you're talking about. to address this we use (sysctl) vm.dirty_expire_centisecs vm.dirty_writeback_centisecs furthermore check the fs alignment with the underlying disk ... -- LF

I've had a few systems with a lot of RAM and very busy filesystems come up with filesystem errors that took a manual 'fsck -y' after what should have been a clean reboot. This is particularly annoying on remote systems where I have to talk someone else through the recovery. Is there some time limit on the cache write with a 'reboot' (no options) command or is ext4 that

...write-back cache enabled (BBU is good). RAID controller logs are free of errors. NFS servers used dual bonded gigabit links in balance-alb mode. Turning off one interface in the bond made no difference. Relevant /etc/sysctl.conf parameters: vm.dirty_ratio = 50 vm.dirty_background_ratio = 1 vm.dirty_expire_centisecs = 1000 vm.dirty_writeback_centisecs = 100 vm.min_free_kbytes = 65536 net.core.rmem_default = 262144 net.core.rmem_max = 262144 net.core.wmem_default = 262144 net.core.wmem_max = 262144 net.core.netdev_max_backlog = 25000 net.ipv4.tcp_reordering = 127 net.ipv4.tcp_rmem = 4096 87380 16777216 net.ipv4...

...a 'reboot' (no > options) command or is ext4 that fragile? I'd say there's no limit in the amount of time the kernel waits until the blocks have been written to disk; driven by there parameters: vm.dirty_background_bytes = 0 vm.dirty_background_ratio = 10 vm.dirty_bytes = 0 vm.dirty_expire_centisecs = 3000 vm.dirty_ratio = 20 vm.dirty_writeback_centisecs = 500 ie, if the data cached on RAM is older than 30s or larger than 10% available RAM, the kernel will try to flush it to disk. Depending how much data needs to be flushed at poweroff/reboot time, this could have a significant effect on the...

...instances, typically 5Gb with 1Gb swap. Dual / Dual Core 2.8G Xeon (4 in total) with 6Gb RAM. Twin 500Gb SATA HDD (software RAID1) To my way of thinking (!) when it runs out of memory, it should force a sync (or similar) and it''s not, it''s just sitting there. If I wait for the dirty_expire_centisecs timer to expire, I may get some life back, some instances will survive and some will have hung. Here''s a working "meminfo"; MemTotal: 860160 kB MemFree: 22340 kB Buffers: 49372 kB Cached: 498416 kB SwapCached: 15096 kB Active: 92452 kB Inactive: 491840 kB SwapTotal: 41...

Hi All We use CentOS 6.6 for our application. I have profiled the application and find that we have a heavy requirement in terms of Disk writes. On an average when our application operates at a certain load i can observe that the disk writes / second is around 2 Mbps (Average). The block size set is 4k ******************* [root at localhost ~]# blockdev --getbsz /dev/sda3 4096

...be LVM inside VM on top of LVM on KVM host problem too? small chance probably because the first 10 - 20GB it works great!) - tried disabling Selinux, upgrading to newest kernels (elrepo ml and lt), played around with dirty_cache thingeys like proc/sys/vm/dirty_writeback_centisecs /proc/sys/vm/dirty_expire_centisecs cat /proc/sys/vm/dirty_ratio , and migration threashold of dmsetup, and other probably non important stuff like vm.dirty_bytes - when in "slow state" the systems kworkers are exessively using IO (10 - 20 MB per kworker process). This seems to be the writeback process (CPY%Sync) becau...

...mand or is ext4 that fragile? > > I'd say there's no limit in the amount of time the kernel waits until > the blocks have been written to disk; driven by there parameters: > > vm.dirty_background_bytes = 0 > vm.dirty_background_ratio = 10 > vm.dirty_bytes = 0 > vm.dirty_expire_centisecs = 3000 > vm.dirty_ratio = 20 > vm.dirty_writeback_centisecs = 500 > > ie, if the data cached on RAM is older than 30s or larger than 10% > available RAM, the kernel will try to flush it to disk. Depending how > much data needs to be flushed at poweroff/reboot time, this could hav...

...gepagesize: 2048 kB DirectMap4k: 10232 kB DirectMap2M: 901120 kB sysctl: vm.oom_dump_tasks = 0 vm.oom_kill_allocating_task = 1 vm.panic_on_oom = 1 vm.admin_reserve_kbytes = 8192 vm.block_dump = 0 vm.dirty_background_bytes = 0 vm.dirty_background_ratio = 10 vm.dirty_bytes = 0 vm.dirty_expire_centisecs = 3000 vm.dirty_ratio = 20 vm.dirty_writeback_centisecs = 500 vm.drop_caches = 0 vm.highmem_is_dirtyable = 0 vm.hugepages_treat_as_movable = 0 vm.hugetlb_shm_group = 0 vm.laptop_mode = 0 vm.legacy_va_layout = 0 vm.lowmem_reserve_ratio = 256 32 32 vm.max_map_count = 65530 vm.min_free_kbytes =...

...top of LVM on KVM host problem too? small chance probably > because the first 10 - 20GB it works great!) > > - tried disabling Selinux, upgrading to newest kernels (elrepo ml and lt), > played around with dirty_cache thingeys like proc/sys/vm/dirty_writeback_centisecs > /proc/sys/vm/dirty_expire_centisecs cat /proc/sys/vm/dirty_ratio , and > migration threashold of dmsetup, and other probably non important stuff > like vm.dirty_bytes > > - when in "slow state" the systems kworkers are exessively using IO (10 - > 20 MB per kworker process). This seems to be the writeback proc...

...roblem too? small chance probably because the first 10 - 20GB it > works great!) > > - tried disabling Selinux, upgrading to newest kernels (elrepo ml > and lt), played around with dirty_cache thingeys like > proc/sys/vm/dirty_writeback_centisecs > /proc/sys/vm/dirty_expire_centisecs cat /proc/sys/vm/dirty_ratio , > and migration threashold of dmsetup, and other probably non > important stuff like vm.dirty_bytes > > - when in "slow state" the systems kworkers are exessively using > IO (10 - 20 MB per kworker process). This seems to be th...

I believe 30 sec is the default for the checkpoint interval.  Is this adjustable? -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html