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Questions tagged [performance-tuning]

Performance tuning is the process of modifying a system to improve its efficiency. This is also known as optimizing.

Performance tuning is the process of modifying a system to improve its efficiency. This is also known as optimizing.

Typically performance tuning refers to a computer application, but the same methods can be applied to other complex systems. The system can be a single computer program, a collection of computers or even an application.

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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 100,000-200,000 active connections. Newer versions of…
SaveTheRbtz
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Why is my bare-metal 16x 2.93GHz cores computer performing poorer than a VPS with 4x 2.5GHz cores?

I have a written a piece of multi-threaded software that does a bunch of simulations a day. This is a very CPU-intensive task, and I have been running this program on cloud services, usually on configurations like 1GB per core. I am running CentOS…
Glauco Cattalini Lins
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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 feel of my web app's database performance.
Bill Paetzke
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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 setups that incorporate hardware RAID controllers…
ewwhite
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How do I tell how close I'm getting to somaxconn?

The sysctl option net.core.somaxconn defaults to 128 (on our systems) but can be raised. What exactly is this limit measuring and capping? How do I find out how close I am to the limit? Context: I had a problem recently that appeared to be…
Andrew
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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 issuing these etags correctly ?
MikeJ
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Tuning (and understanding) table_cache in mySQL

I ran the excellent MySQL performance tuning script and started to work through the suggestions. One I ran into was TABLE CACHE Current table_cache value = 4096 tables You have a total of 1073 tables. You have 3900 open tables. Current…
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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 StartServers 20 MinSpareServers 100 MaxSpareServers…
ServerChecker
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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 webservice which takes almost 300 seconds to…
john titus
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Building a 1,000M row MySQL table

This question is reposted from Stack Overflow based on a suggestion in the comments, apologies for the duplication. Questions Question 1: as the size of the database table gets larger how can I tune MySQL to increase the speed of the LOAD DATA…
Ben
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Find out which task is generating a lot of context switches on linux

According to vmstat, my Linux server (2xCore2 Duo 2.5 GHz) is constantly doing around 20k context switches per second. # vmstat 3 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si…
grzaks
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Virtual machines and I/O heavy workload, is it ever sane?

I have seen on numerous virtualization services (Azure) and products (vmware,kvm,hyperv) I/O and system stalls under heavy I/O workload. My questions are: Is it ever sane to use a Virtualized solution when performing I/O heavy workloads? What are…
bryan hunt
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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 processors x 4 cores - Intel(R) Xeon(R) CPU E5345…
Alex V
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Should we mount with data=writeback and barrier=0 on ext3?

We've been running a server on a VM at a hosting company, and have just signed up for a dedicated host (AMD Opteron 3250, 4 cores, 8GB RAM, 2 x 1TB in software RAID, ext3). While running performance tests, we noticed that some SQLite transations…
NeilB
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Virtualization - Ten 1Gbps links or one 10Gbps link? (Performance)

I have a machine that has several VM's (5) and 3 physical networking cards (with each 2 ports), with a total of six 1Gbps ethernet ports. I have a SPF-capable switch, having a total of 48Gbps bandwidth and a 10Gbps SPF link. The server has also one…
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