Questions tagged [performance-tuning]
Performance tuning is the process of modifying a system to improve its efficiency. This is also known as optimizing.
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Linux - real-world hardware RAID controller tuning (scsi and cciss)
Most of the Linux systems I manage feature hardware RAID controllers (mostly HP Smart Array). They're all running RHEL or CentOS.
I'm looking for real-world tunables to help optimize performance for ...
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Openfiler iSCSI performance
Hoping someone can point me in the right direction with some iSCSI performance issues I'm having. I'm running Openfiler 2.99 on an older ProLiant DL360 G5. Dual Xeon processor, 6GB ECC RAM, Intel ...
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Understanding RedHat's recommended tuned profiles
We are going to roll out tuned (and numad) on ~1000 servers, the majority of them being VMware servers either on NetApp or 3Par storage.
According to RedHats documentation we should choose the ...
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HP P410 RAID + Samsung 830 SSDs + Debian 6.0 - What performance to expect?
I'm renting two dedicated servers from a hosting company. Here are the specs:
server1:
HP ProLiant DL165 G7
2x AMD Opteron 6164 HE 12-Core
40 GB RAM
HP Smart Array P410 RAID controller
2x Samsung 830 ...
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yslow says etags are misconfigured. how to configure etags properly on IIS7?
running ySlow on a website I support, I noticed it reported that the etags are misconfigured for the site images (e.g. *.jpg, *.png, *.gif). Can anyone help explain what I have to do to get IIS7 ...
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Configuring NTFS file system for performance
We have an application that is planning to store around 1.1TB of XML files which average 8.5kb in size.
These represent a rolling 18 months of data, with around 200,000 new files being created every ...
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2
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How do I disable "Processor Power and Utilization Monitoring" on an HP ProLiant server?
I'm tuning my server for low-latency. The HP low-latency guide suggests to disable this option "Processor Power and Utilization Monitoring" because:
Disables iLO Processor State Mode Switching
and ...
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4
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FreeBSD performance tuning: Sysctl parameter, loader.conf, kernel
I wanted to share knowledge of tuning FreeBSD via sysctl.conf / loader.conf
/ KENCONF / etc. It was initially based on Igor Sysoev's (author of nginx)
presentation about FreeBSD tuning up to 100,000-...
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How To Tune Apache on Ubuntu 14.04 Server
Currently on my Apache 2 (Apache 2.4.7 to be exact) on Ubuntu 14.04, I have this setting:
/etc/apache2/mods-enabled/mpm_prefork.conf
<IfModule mpm_prefork_module>
StartServers ...
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3
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CPU0 is swamped with eth1 interrupts
I've got an Ubuntu VM, running inside Ubuntu-based Xen XCP. It hosts a custom FCGI-based HTTP service, behind nginx.
Under load from ab the first CPU core is saturated, and the rest is under-loaded.
...
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1
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difference between taskset and cpuset
I'm trying to reduce the latency of my linux network application. I've learned that there are two tools for "binding" a program to particular CPU core: taskset and cpuset.
Which one should I prefer? ...
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Does 'tuned' need to keep running?
On my CentOS 7 systems, I use tuned-adm to set a profile appropriate to the environment during configuration, but after that, I never subsequently change that profile. It seems that the tuned system ...
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Linux's best filesystem to work with 10000's of files without overloading the system I/O
It is known that certain AMD64 Linuxes are subject of being unresponsive under heavy disk I/O (see Gentoo forums: AMD64 system slow/unresponsive during disk access (Part 2)), unfortunately have such ...
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Slow write Performance with HP H240 HBA using internal Storage with Raid 5 SSD's
I am having a HP Proliant DL 160 Gen9 Server with a HP H240 Host Bus Adapter.
6x 1 TB Samsung SSD's configured in a raid 5 directly using the internal storage of the machine.
After installing a VM on ...
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Is it OK to run perfmon on production servers? And why?
Or should perfmon be limited to a Dev/QA server with load tests that simulate production activity?
I'd like to run perfmon for two days (like Sql Server master Brent Ozar suggests) to get an overall ...
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Apache Tomcat chokes after 300 connections
We have an apache webserver in front of Tomcat hosted on EC2, instance type is extra large with 34GB memory.
Our application deals with lot of external webservices and we have a very lousy external ...
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Low latency TCP settings on Ubuntu
There is a server for measurements running on Ubuntu in my lab. And there is C program, which receives data through TCP connection and should as soon as possible send a reply.
Configuration
CPUs: 2 ...
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13
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Postfix performance
Running postfix on ubuntu, sending alot of mail ( ~ 1 million messages ) per day. loads are extremly high but not much in terms of cpu and memory load. Anyone in a similiar situation and know how to ...
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Too much I/O generated by postgres stats collector process
I am using XenServer with several virtual machines having local postgres databases. Even when all applications are unused and the databases are idle, each vm causes constant storage network traffic ...
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1
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Why change net.inet.tcp.tcbhashsize in FreeBSD?
In virtually every FreeBSD network tuning document I can find:
# /boot/loader.conf
net.inet.tcp.tcbhashsize=4096
This is usually paired with some unhelpful statement like "TCP control-block hash ...
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How long is the "defined grace period" for the idle scheduling class of the CFQ io scheduler?
The ionice man page says
A program running with idle io priority will only get disk time
when no other program has asked for disk io for a defined grace period.
Where is this "grace period" ...
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Linux tool/command to check file system performance
What is the simplest way to check read/write performance to a specific location (e.g. a mounted iSCSI device).
I suspect I can't use hdparm because that's lower level. Am I right?
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Hard Drive Speed: RPM vs. Cache
When trying to choose a SATA magnetic hard drive (not SSD) for high performance for both random and linear access, which should be the primary factor?
For example: would a 10k RPM drive with 16MB ...
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1
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Lot of FIN_WAIT2, CLOSE_WAIT , LAST_ACK and TIME_WAIT in Haproxy
We are running haproxy in production for around 10k+ concurrent users. But we are seeing lot of FIN_WAIT2, CLOSE_WAIT , LAST_ACK and TIME_WAIT in the netstat output. This output is on a 8G ubuntu-12....
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Uneven CPU core utilization
tl;dr: First CPU core is consistently saturated, all other cores are consistently under-loaded.
A VM, inside Ubuntu-based Xen XCP:
$ uname -a
Linux MYHOST 2.6.38-15-virtual #59-Ubuntu SMP Fri Apr 27 ...
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How do I test the effect of ionice (against a device using the cfq scheduler)?
I'm trying to construct an experiment to measure the effect of ionice. What I'd like to do is to (per another answer on serverfault) cause frequent enough I/O that a sufficiently "niced" process is ...
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1
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Ubuntu HTTP latency falling into strange quantiles
I have an Ubuntu 10.10 server with plenty of RAM, bandwidth and CPU. I'm seeing a strange, repeatable pattern in the distribution of latencies when serving static files from both Apache and nginx. ...
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Very low performance of raid6
I noticed that writing to raid-6 is very low, but when I make tests with hdparm the speed is reasonable:
dd if=/dev/zero of=/store/01/test.tmp bs=1M count=10000
Gives: 50Mb/s or even less.
The ...
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NFS Over OpenVPN: Top Performance Boosters
I have two VPS's - One is running 2008 Server R2 and the other is a Ubuntu 12.04 installation. I am using the Windows VPS for RD sessions for Quickbooks and a couple other apps and using the Ubuntu ...
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Running "find" command generates high load
I run this command on a Debian server with SSD drives configured as RAID 1:
ionice -c 3 find . -type f -amin -1440 -mmin +1441 -not -path custom/ -print0
on a path which contains over 1.7M files and ...
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Disabling CPU management
If I add the following processor.max_cstate=0 to the kernel command line for boot up, does that disable all CPU power management and throttling?
I also found:
http://www.experts-exchange.com/OS/Linux/...
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How can I improve NFS performance on a gigabit LAN?
I have a Solaris 10 server with a Mac OS X clients on a gigabit LAN. The Solaris server exports a RAID-Z backed NFS share and all the clients connect to it. However, transferring files is slower ...
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Troubleshooting poor disk IO performance
Note that while this question is a little Redis-specific, the main problem is generic: a process takes so much HDD IO write bandwidth that other processes can't write anything.
We've got an Ubuntu VM ...
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What does the following C-State output mean?
# cat /proc/acpi/processor/CPU0/power
active state: C0
max_cstate: C8
maximum allowed latency: 2000000000 usec
states:
C1: type[C1] promotion[--] demotion[-...
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Server problems, running out of RAM, really high load average
I desperately need help in figuring out how to troubleshoot this problem I'm having. I run a fairly mission critical web server (Debian 7.5, 512MB RAM, 512MB swap, Apache, MySQL). It runs a couple ...
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Server optimization for long running script [duplicate]
I have a system running on a remote VPS whose main feature is a long running script (it could run for about 10 hours, depending on the user input).
The following are some of its features:
Database ...
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1
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HP DL360p Gen8 for low latency trading - what to upgrade? [closed]
I'm using HP DL360p Gen8 for low latency trading (but not ultra-low-latency!).
It means that i'm working in frame about "10+ microseconds" and i don't care about "1-5 microsecond" or nanoseconds.
I ...
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