Amazon Linux 2

This page describes the Optimization Pack for the component type Amazon Linux 2.

Metrics

CPU

Metric		Description
cpu_load_avg	tasks	The system load average (i.e., the number of active tasks in the system)
cpu_num	CPUs	The number of CPUs available in the system (physical and logical)
cpu_util	percent	The average CPU utilization % across all the CPUs (i.e., how much time on average the CPUs are busy doing work)
cpu_used	CPUs	The average number of CPUs used in the system (physical and logical)
cpu_util_details	percent	The average CPU utilization % broken down by usage type and CPU number (e.g., cp1 user, cp2 system, cp3 soft-irq)

Memory

Metric		Description
mem_fault	faults/s	The number of memory faults (minor+major)
mem_fault_major	faults/s	The number of major memory faults (i.e., faults that cause disk access) per second
mem_fault_minor	faults/s	The number of minor memory faults (i.e., faults that do not cause disk access) per second
mem_swapins	pages/s	The number of memory pages swapped in per second
mem_swapouts	pages/s	The number of memory pages swapped out per second
mem_total	bytes	The total amount of installed memory
mem_used	bytes	The total amount of memory used
mem_used_nocache	bytes	The total amount of memory used without considering memory reserved for caching purposes
mem_util	percent	The memory utilization % (i.e, the % of memory used)
mem_util_details	percent	The memory utilization % (i.e., the % of memory used) broken down by usage type (e.g., active memory)
mem_util_nocache	percent	The memory utilization % (i.e., the % of memory used) without considering memory reserved for caching purposes

Disk & Filesystem

Metric		Description
disk_io_inflight_details	ops	The number of IO disk operations in progress (outstanding) broken down by disk (e.g., disk /dev/nvme01)
disk_iops	ops/s	The average number of IO disk operations per second across all disks
disk_iops_details	ops/s	The number of IO disk-write operations per second broken down by disk (e.g., disk /dev/nvme01)
disk_iops_reads	ops/s	The average number of IO disk-read operations per second across all disks
disk_iops_writes	ops/s	The average number of IO disk-write operations per second across all disks
disk_read_bytes	bytes/s	The number of bytes per second read across all disks
disk_read_bytes_details	bytes/s	The average response time of IO disk operations broken down by disk (e.g., disk C://)
disk_read_write_bytes	bytes/s	The number of bytes per second written across all disks
disk_response_time_details	seconds	The average response time of IO disk operations broken down by disk (e.g., disk C://)
disk_response_time_read	seconds	The average response time of read disk operations
disk_response_time_worst	seconds	The average response time of IO disk operations of the slowest disk
disk_response_time_write	seconds	The average response time of write on disk operations
disk_swap_used	bytes	The total amount of space used by swap disks
disk_swap_util	percent	The average space utilization % of swap disks
disk_util_details	percent	The utilization % of disk, i.e how much time a disk is busy doing work broken down by disk (e.g., disk D://)
disk_write_bytes	bytes/s	The number of bytes per second written across all disks
disk_write_bytes_details	bytes/s	The number of bytes per second written from the disks broken down by disk and type of operation (e.g., disk /dev/nvme01 and operation WRITE)
filesystem_size	bytes	The size of filesystems broken down by type and device (e.g., filesystem of type ext4 for device /dev/nvme01)
filesystem_used	bytes	The amount of space used on the filesystems broken down by type and device (e.g., filesystem of type zfs on device /dev/nvme01)
filesystem_util	percent	The space utilization % of filesystems broken down by type and device (e.g., filesystem of type overlayfs on device /dev/loop1)

Network

Metric		Description
network_in_bytes_details	bytes/s	The number of inbound network packets in bytes per second broken down by network device (e.g., wlp4s0)
network_out_bytes_details	bytes/s	The number of outbound network packets in bytes per second broken down by network device (e.g., eth01)
network_tcp_retrans	retrans/s	The number of network TCP retransmissions per second

Others

Metric		Description
os_context_switch	switches/s	The number of context switches per second
proc_blocked	processes	The number of processes blocked (e.g, for IO or swapping reasons)

Parameters

CPU

Parameter	Type	Unit	Default Value	Domain	Restart	Description
os_cpuSchedMinGranularity	integer	nanoseconds	1500000	300000 → 30000000	no	Minimal preemption granularity (in nanoseconds) for CPU bound tasks
os_cpuSchedWakeupGranularity	integer	nanoseconds	2000000	400000 → 40000000	no	Scheduler Wakeup Granularity (in nanoseconds)
os_CPUSchedMigrationCost	integer	nanoseconds	500000	100000 → 5000000	no	Amount of time (in nanoseconds) after the last execution that a task is considered to be "cache hot" in migration decisions. A "hot" task is less likely to be migrated to another CPU, so increasing this variable reduces task migrations
os_CPUSchedChildRunsFirst	integer		0	0, 1	no	A freshly forked child runs before the parent continues execution
os_CPUSchedLatency	integer	nanoseconds	12000000	2400000 → 240000000	no	Targeted preemption latency (in nanoseconds) for CPU bound tasks
os_CPUSchedAutogroupEnabled	integer		0	0, 1	no	Enables the Linux task auto-grouping feature, where the kernel assigns related tasks to groups and schedules them together on CPUs to achieve higher performance for some workloads
os_CPUSchedNrMigrate	integer		32	3 → 320	no	Scheduler NR Migrate

Memory

Parameter	Type	Unit	Default Value	Domain	Restart	Description
os_MemorySwappiness	integer	percent	60	0 → 100	no	The percentage of RAM free space for which the kernel will start swapping pages to disk
os_MemoryVmVfsCachePressure	integer		100	10 → 100	no	VFS Cache Pressure
os_MemoryVmCompactionProactiveness	integer		20	0 → 100		Determines how aggressively compaction is done in the background
os_MemoryVmPageLockUnfairness	integer		5	0 → 1000	no	Set the level of unfairness in the page lock queue.
os_MemoryVmWatermarkScaleFactor	integer		10	0 → 1000	no	The amount of memory, expressed as fractions of 10'000, left in a node/system before kswapd is woken up and how much memory needs to be free before kswapd goes back to sleep
os_MemoryVmWatermarkBoostFactor	integer		15000	0 → 30000	no	The level of reclaim when the memory is being fragmented, expressed as fractions of 10'000 of a zone's high watermark
os_MemoryVmMinFree	integer		67584	10240 → 1024000	no	Minimum Free Memory (in kbytes)
os_MemoryTransparentHugepageEnabled	categorical		madvise	always, never, madvise	no	Transparent Hugepage Enablement Flag
os_MemoryTransparentHugepageDefrag	categorical		madvise	always, never, defer+madvise, madvise, defer	no	Transparent Hugepage Enablement Defrag
os_MemorySwap	categorical		swapon	swapon, swapoff	no	Memory Swap
os_MemoryVmDirtyRatio	integer		20	1 → 99	no	When the dirty memory pages exceed this percentage of the total memory, processes are forced to write dirty buffers during their time slice instead of continuing to write
os_MemoryVmDirtyBackgroundRatio	integer		10	1 → 99	no	When the dirty memory pages exceed this percentage of the total memory, the kernel begins to write them asynchronously in the background
os_MemoryVmDirtyExpire	integer	centiseconds	3000	300 → 30000	no	When the dirty memory pages exceed this percentage of the total memory, processes are forced to write dirty buffers during their time slice instead of continuing to write
os_MemoryVmDirtyWriteback	integer	centiseconds	500	50 → 5000	no	Memory Dirty Writeback (in centisecs)

Network

Parameter	Type	Unit	Default Value	Domain	Restart	Description
os_NetworkNetCoreSomaxconn	integer	megabytes	128	12 → 8192	no	Network Max Connections
os_NetworkNetCoreNetdevMaxBacklog	integer	megabytes/s	1000	100 → 10000	no	Network Max Backlog
os_NetworkNetIpv4TcpMaxSynBacklog	integer	milliseconds	256	52 → 5120	no	Network IPV4 Max Sync Backlog
os_NetworkNetCoreNetdevBudget	integer		300	30 → 30000	no	Network Budget
os_NetworkNetCoreRmemMax	integer		212992	21299 → 2129920	no	Maximum network receive buffer size that applications can request
os_NetworkNetCoreWmemMax	integer		212992	21299 → 2129920	no	Maximum network transmit buffer size that applications can request
os_NetworkNetIpv4TcpSlowStartAfterIdle	integer		1	0, 1	no	Network Slow Start After Idle Flag
os_NetworkNetIpv4TcpFinTimeout	integer		60	6 → 600	no	Network TCP timeout
os_NetworkRfs	integer		0	0 → 131072	no	If enabled increases datacache hitrate by steering kernel processing of packets to the CPU where the application thread consuming the packet is running

Storage

Parameter	Type	Unit	Default Value	Domain	Restart	Description
os_StorageReadAhead	integer	kilobytes	128	0 → 4096	no	Read-ahead speeds up file access by pre-fetching data and loading it into the page cache so that it can be available earlier in memory instead of from disk
os_StorageNrRequests	integer		32	12 → 1280	no	Storage Number of Requests
os_StorageRqAffinity	integer		1	1, 2	no	Storage Requests Affinity
os_StorageQueueScheduler	integer		none	none, kyber, mq-deadline, bfq	no	Storage Queue Scheduler Type
os_StorageNomerges	integer		0	0 → 2	no	Enables the user to disable the lookup logic involved with IO merging requests in the block layer. By default (0) all merges are enabled. With 1 only simple one-hit merges will be tried. With 2 no merge algorithms will be tried
os_StorageMaxSectorsKb	integer	kilobytes	256	32 → 256	no	The largest IO size that the OS can issue to a block device