Difference between revisions of "OS: Tuning Kernel Scheduler"
Onnowpurbo (talk | contribs) |
Onnowpurbo (talk | contribs) |
||
| Line 306: | Line 306: | ||
* [[OS: Kernel Scheduler]] | * [[OS: Kernel Scheduler]] | ||
* [[OS: Tuning Kernel Scheduler]] | * [[OS: Tuning Kernel Scheduler]] | ||
| + | * [[OS: Complete Teori Tuning Kernel Scheduler]] | ||
* [[OS: Tuning Completely Fair Queueing CFQ I/O scheduler]] | * [[OS: Tuning Completely Fair Queueing CFQ I/O scheduler]] | ||
* [[OS: Tuning Completely Fair scheduler CFS]] | * [[OS: Tuning Completely Fair scheduler CFS]] | ||
* [[OS: Build in Monitoring Tool]] | * [[OS: Build in Monitoring Tool]] | ||
* [[OS: Benchmarking menggunakan UnixBench]] | * [[OS: Benchmarking menggunakan UnixBench]] | ||
Revision as of 10:15, 10 March 2013
Mengapa tune kernel?
Perilaku default kernel UNIX biasanya tidak optimal karena sulit untuk mengantisipasi jenis pekerjaan atau beban kerja yang akan diberikan kepada sistem operasi . Oleh karena itu, UNIX menyediakan parameter yang dapat mengubah alokasi sumber daya. Parameter kernel tuning adalah spesifik UNIX.
Administrator sistem bertanggung jawab untuk menentukan jenis target pekerjaan dan beban kerja untuk mesin dan untuk memantau apakah terjadi perubahan dari waktu ke waktu. Administrator sistem harus memastikan bahwa setiap parameter kernel diatur untuk mengoptimalkan kinerja mesin.
CATATAN: Tuning Kernel merupakan topik lanjut dan tidak boleh dilakukan tanpa pemahaman lengkap tentang hal tersebut.
Kernel tuning with sysctl
Sumber: http://archive09.linux.com/feature/146599 Oleh Federico Kereki 9 September 2008 (4:00:00 PM)
Kernel Linux cukup fleksibel, kita bahkan dapat memodifikasi cara kerjanya sambil komputer jalan secara dinamis mengubah beberapa parameter, berkat perintah sysctl. Sysctl menyediakan sebuah antarmuka yang memungkinkan kita untuk memeriksa dan mengubah ratusan parameter kernel di Linux atau BSD. Perubahan segera berlaku, dan bahkan ada cara untuk membuat parameter tersebut tidak hilang setelah reboot. Dengan menggunakan sysctl secara bijak, kita dapat mengoptimalkan komputer tanpa harus mengkompilasi ulang kernel , dan mendapatkan hasilnya dengan cepat.
Untuk mendapatkan sedikit rasa parameter apa saja yang dapat di modifikasi oleh sysctl, jalankan sysctl -a
$ sysctl -a
Hasilnya
kernel.sched_child_runs_first = 0 kernel.sched_min_granularity_ns = 1500000 kernel.sched_latency_ns = 12000000 kernel.sched_wakeup_granularity_ns = 2000000 kernel.sched_tunable_scaling = 1 kernel.sched_migration_cost = 500000 kernel.sched_nr_migrate = 32 kernel.sched_time_avg = 1000 kernel.sched_shares_window = 10000000 kernel.timer_migration = 1 kernel.sched_rt_period_us = 1000000 kernel.sched_rt_runtime_us = 950000 kernel.sched_autogroup_enabled = 1 kernel.sched_cfs_bandwidth_slice_us = 5000 kernel.panic = 0 ... dan seterusnya ...
Jika kita ingin mendapatkan nilai hanya satu variabel, gunakan perintah seperti
sysctl vm.swappiness
atau hanya
sysctl vm
untuk daftar semua variabel yang dimulai dengan "vm." Tambahkan opsi -n untuk mengeluarkan hanya nilai variabel, tanpa nama,-N memiliki efek sebaliknya, dan menghasilkan nama-nama tapi tidak nilai.
Kita dapat mengubah nlai variabel dengan menggunakan opsi-w dengan sintaks
sysctl -w variable=nilai
Misalnya,
sysctl -w net.ipv6.conf.all.forwarding=1
set variabel menjadi benar / true (0 sama dengan "tidak" atau "salah", 1 berarti "ya" atau "benar") sehingga memungkinkan IP6 forwarding. Anda mungkin tidak membutuhkan opsi -w tampaknya akan usang.
Informasi lebih lanjut tentang sysctl dapat di baca dengan cara mengetik
man sysctl
sysctl dan directory /proc
Virtual directory /proc/sys juga memberikan interface ke parameter sysctl memungkinkan kita untuk melihat dan mengubah parameter tersebut. Contoh, file /proc/sys/vm/swappiness sama dengan parameter vm.swappiness parameter di sysctl.conf. Oleh karenanya, melakukan
echo 10 >/proc/sys/vm/swappiness
sama dengan
sysctl -w vm.swappiness=10
Yang perlu kita perhatikan, jika file /proc/sys read-only, maka kita tidak akan bisa mengubahnya juga dengan sysctl.
Tulis
ls /proc/sys/kernel
untuk melihat parameter kernel yang bisa kita ubah.
sysctl.conf
Nilai paramter sysctl akan di load dari file /etc/sysctl.conf saat boot. File ini dapat memiliki baris kosong, komen (start dengan #), dan baris dengan format "variable=nilai" format. Contoh isi sysctl.conf adalah sebagai berikut,
# Disable response to broadcasts. net.ipv4.icmp_echo_ignore_broadcasts = 1 # enable route verification on all interfaces net.ipv4.conf.all.rp_filter = 1 # enable ipV6 forwarding net.ipv6.conf.all.forwarding = 1 # increase the number of possible inotify(7) watches fs.inotify.max_user_watches = 65536
Jika kita ingin mengaktifkan / mereload parameter sysctl, dapat dilakukan dengan perintah
sysctl -p.
Sumber: http://www.techtinker.com/linux/LinuxKernel.html#HowRedHat
Contoh Tuning Kernel untuk Oracle9i
Contoh berikut adalah tuning Linux Kernel sebelum menginstalasi Oracle9i atau Oracle Applications 11i.
Edit file /etc/sysctl.conf
vi /etc/sysctl.conf
Contoh konfigurasi
# -------------------------------------------------------------------------
# Kernel parameter assumptions and rationale.
# ===========================================
# -------------------------------------------------------------------------
# Disables packet forwarding
# -------------------------------------------------------------------------
net.ipv4.ip_forward = 0
# -------------------------------------------------------------------------
# Enables source route verification
# -------------------------------------------------------------------------
net.ipv4.conf.default.rp_filter = 1
# -------------------------------------------------------------------------
# Set the default local port range.
# -------------------------------------------------------------------------
net.ipv4.ip_local_port_range = 1024 65000
# -------------------------------------------------------------------------
# Enables the magic-sysrq key
# -------------------------------------------------------------------------
kernel.sysrq = 1
# -------------------------------------------------------------------------
# General semaphore rules:
# -----------------------
# 1. Semaphore tunable parameters are limited to semmsl, semmns,
# semopm and semmni and must be entered in the /etc/sysctl.conf
# file with the following syntax.
#
# kernel.sem = semmsl semmns semopm semmni
#
# 2. The tunable kernel resource of semmsl sets the maximum number
# of semaphore per set. The semopm should be set equal to semmsl
# so that an operation can be performed on every semaphore in
# the set. If semopm is larger than semmsl it should raise an
# OS exception but doesn't in Linux.
#
# Oracle8i Installation Manual for UNIX recommends this value be
# derived as "... the sum of the PROCESSES parameter for each
# Oracle database except the largest one, plus 2 times the largest
# PROCESSES value, plus 10 times the number of Oracle databases."
# Assuming 2 Oracle8i databases with the init{SID}.ora "processes"
# parameter set to 100 and 1 Oracle 9iAS server with "processes"
# parameter set to 100, the following is the recommended value:
#
# Variables:
# =========
# s = sum of processes for all but largest instance
# m = maximum number of process for a single instance
# n = total number of instances
# i = n - largest instance.
#
# semmsl = ((s * i) + (m * 2)) + (n * 10))
#
# semmsl = ((100*2) + (100)*2) + (3 * 10)) = (400 + 30) = 430
#
# semopm = semmsl = 430
#
# 3. The tunable kernel resource of semmni sets the system wide
# semaphore sets by creating a semid_ds control structure of
# 84 bytes, so this parameter should not be set arbitrarily large.
# The Oracle8i and Oracle9i installation manual recommends 100
# for each Oracle instance. Assuming 2 Oracle8i databases with
# the init{SID}.ora processes parameter set to 100 and 1 Oracle
# 9iAS server with processes parameter set to 100, the following
# is the recommended value:
#
# semmni = 300
#
# 4. The semmsl (maximum number of semaphores per identifier) value
# is the product of the semmni and semmsl values, as qualified
# below:
#
# semmns = (semmni * semmsl) = 300 * 430 = 129000
#
# 5. Therefore, semaphores should be set in the /etc/sysctl.conf
# file as follows:
# -------------------------------------------------------------------------
kernel.sem = 430 129000 430 300
# -------------------------------------------------------------------------
# General semaphore rules:
# -----------------------
# 1. The "Oracle9i Installation Guide, Release 2 (9.2.0.1.0) for
# UNIX Systems: AIX-Based Systems, Compaq Tru64 UNIX, HP 9000
# Series HP-UX, Linux Intel, and Sun Solaris" manual (A96167)
# advises default settings for shmmin, shmmni, shmseg and
# shmvmx shared memory kernel values.
#
# 2. The shmmin should be set to 1.
#
# 3. The shmmni memory variable sets the maximum number of
# system wide shmid_ds structures and should be equal to the
# value determined for semmni value.
#
# shmmni = semmni = 300
#
# 4. The shmmax should be set to 50% of available memory or 2 GB but
# setting above 50% of available memory can cause some memory use
# issues in Oracle8i.
#
# 5. The shmmin, shmmsg and shmvmx cannot be set when using the
# Red Hat Advanced Server 2.1 because alteration of the kernel is
# not supported by Oracle and these typically tunable parameters
# are fixed in the supported and shipped kernels.
#
# -------------------------------------------------------------------------
kernel.shmmni = 300
kernel.shmmax = 2147483648
# -------------------------------------------------------------------------
# General File Management:
# -----------------------
# The default value of 8192 is not compatible with Oracle's file limit
# of 65536 and should be changed to that value or higher provided memory
# is available. For example, the typical rule-of-thumb is to divide real
# memory by 16,384, or 64 simultaneous open files per 1 MB of memory.
# In systems with large amounts of memory, concurrency of file access
# would be a better rule-of-thumb. The value is set based on 2 GB of
# real memory as follows below.
#
# fs.file-max = ( 2,097,152,000 / 16384 ) = 128,000
#
# Using the 2.2.x Linux kernel you will need to set the inode-max
# value to 4 to 5 times the file-max value. However, beginning with the
# 2.4.x Linux kernel inode-max is managed dynamically and should not be
# set in the /etc/sysctl.conf file.
# -------------------------------------------------------------------------
fs.file-max=128000
Reboot agar perubahan parameter berefek.
Validasi kernel boot parameter. Setelah booting, cek menggunakan perintah berikut,
sysctl -p | grep kernel
Hasilnya
kernel.sysrq = 0 kernel.core_uses_pid = 1 kernel.sem = 430 129000 430 300 kernel.shmmni = 300 kernel.shmmax = 2147483648
Benchmark
Kadaluarsa
- Kernbench http://freecode.com/projects/kernbench
- Tbench
- Dbench
- SPECJbb
- Hackbench
Referensi
- http://archive09.linux.com/feature/146599
- http://linux.die.net/man/8/sysctl
- http://www.techtinker.com/linux/LinuxKernel.html#HowRedHat
- https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/index.html - BAGUS
- http://www.cs.rochester.edu/u/sanders/linux-scheduler-proj/lottery_scheduler/node2.html
- http://oreilly.com/catalog/linuxkernel/chapter/ch10.html
- http://www.ibm.com/developerworks/linux/library/l-scheduler
- http://events.linuxfoundation.org/slides/2011/linuxcon/lcna2011_rajan.pdf
I/O Scheduler
- http://blog.nexcess.net/2010/11/07/changing-your-linux-io-scheduler/
- http://www.mysqlperformanceblog.com/2009/01/30/linux-schedulers-in-tpcc-like-benchmark/
- http://www.randombugs.com/linux/tuning-linux-system-database.html