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

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12
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7answers
13k views

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 ...
0
votes
1answer
279 views

Linux kernel 3 TCP IP tuning

I found several resources about tuning linux TCP/IP stack parameters in /etc/sysctl.conf for high bandwidth connections, but all refer to kernel 2.6. Does anyone have suggestions about how to tune ...
0
votes
4answers
779 views

Exchange 2010 SP2 OWA performance

How do I increase performance in OWA 2010 SP2? I am running CAS on a seperate installation, which has 8GB RAM and 4 CPU cores - running virtualized in a vmware environment. However, the load times ...
0
votes
2answers
57 views

How can I decide up the nature of performed IO?

I am using Linux (3.2.12-3.2.4). I have few "syncer" processes which updates lots and lots SQLite db files in a loop. The database sizes vary from 1 MB to few GB. I have a "searcher" process which ...
-3
votes
1answer
159 views

Can a large number of network hardware interrupts cause a machine to be underutilized?

I don't know much about networking sorry. I'm building a client / server where the server streams a lot of data to the client and I'm trying to maximise throughput (through TCP). If I run both client ...
3
votes
4answers
1k views

Optimizing RAID 5 for BackupPC use (small random reads)

I am running a BackupPC server with a hardware RAID 5 for the main storage of the backups. Since the machine was created on a tiny budget, the controller is a 3Ware 9500S-4LP for the PCI port and the ...
7
votes
3answers
461 views

Unexplained periodic humps in system CPU usage on W2K3E

We have a Windows 2003 R2 Enterprise 64-bit server running a custom workload suffering from an odd performance problem. The pared-down version below suffers from a smaller hump, but it's qualitatively ...
1
vote
2answers
368 views

Apache2 on linux - how to track down performance trouble

I am stuck on this topic for a while now: How can I get more details on where response time burns. My Problem is the extreme variance in response times. Sometimes it takes the server 5 or 10 seconds ...
0
votes
2answers
1k views

How to turn linux to keep 'cache' high?

We are running a heavy service on Debian. Our service generates lots of file i/o and its performance relies on how well Linux kernel caches files. Our system has 64GB memory. Total file size is 500GB ...
3
votes
2answers
444 views

IIS 7 — how to track down mysterious network & cpu usage?

I've got a 64-bit Server 2008 (R1) box running IIS. Users were complaining about extremely slow-loading pages. After digging around I found: After isolating the box so only one user was able to ...
1
vote
3answers
1k views

Strategy to optimize raid cache

HP SmartArray have "Accelerator Ratio: XX% Read / YY% Write", that configures how much cache ram dedicated for read, and how much for write. Is there way to find best proportion on alive server in ...
-2
votes
1answer
47 views

Ideal number of server, setup and management [closed]

Have read how large scale sites use different servers for different purpose. Here's what I have in mind: Main app - 1 server Database - 1 server Static files - Cloud hosting (e.g. AWS) Backup - 1 ...
21
votes
3answers
8k views

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 ...
7
votes
1answer
1k views

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 ...
5
votes
1answer
852 views

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 ...
3
votes
2answers
148 views

Measuring I/O Performance Paradox

I'm trying to figure out the correct way to get the 'real world' write performance of my NFS cluster. The NFS export is mount on a XEN hypervisor, and I'm running 'dd' from within a VM. What I ...
2
votes
2answers
229 views

How does one 'qualify a server'

Here is the scenario. Say you are going to be a purchasing great deal of servers, but first are trying out hardware from a vendor, and you need to qualify it. Also, say that the custom software that ...
4
votes
1answer
373 views

How does php know what memcached node to look for its data in?

I am new to the world of Memcached clusters If I have a php web application that is using memcache - how does it does its hash and decide what node to check for a particular value to avoid having to ...
0
votes
1answer
161 views

Trade reliability for speed in a slow filesystem

On my box running Ubuntu Server 11.10 I have a rather slow soft RAID6 array on four USB sticks (and no other means for persistent storage). I want a faster filesystem on that box. I'm OK if I'd lose ...
3
votes
1answer
307 views

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" ...
1
vote
5answers
1k views

Windows Server 2008 R2 poor CPU performance

We have two identical servers with the following specs: 4 sockets containing AMD Opteron 6172 at 2.10 GHz each of which have 12 cores 64 GB RAM One runs Windows Server 2008 R2 Standard, which ...
3
votes
1answer
1k views

ApacheTop like tool for Nginx for measuring hit contents?

Are there ApacheTop like tool for Nginx for measuring hit contents? I want to find out the most popular URL from the web server log (Nginx)
4
votes
2answers
596 views

ratelimit POST requests

Im running a large wordpress multiuser site. I have a varnish cache infront of the wordpress application server. As it make no sense to cache POST requests, i am vulnerable to DOS using lots of POST´s ...
0
votes
1answer
84 views

Server stops responding without any load, restart required

Sever is working as a very high-traffic application back-end We are using Apache2, MySql, and PHP. We have already optimized the above for best performance Server configuration is: Linux ...
0
votes
2answers
3k views

How can I configure Apache to use more of my CPU?

Apache threads are stacking up on one of my web servers (300-500 simultaneous requests, some taking 3-8s to process!), but CPU usage is very low (~10%). Page load time is slowing way down as a ...
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votes
1answer
121 views

Apache optimization needed [closed]

What is the best values for "worker" if you have very very high traffic? Like 500M page views per day? I want to test my server with that much traffic but how can i setup to handle that much traffic ...
0
votes
1answer
215 views

adding new scheduling policy to the kernel

i'm working on a redhat 8 linux and i want to add new policy for scheduling the processes , could you help me with : 1) where to define the new policy 2) how does the process of assigning a policy for ...
1
vote
1answer
3k views

Memcached Cluster - better to have 3 smaller instances or 2 mediums ones?

Currently I have 2 small servers in an memcached cluster. We are approaching out limits with them and need to grow. What are the pros/cons or going adding another small instance compared with having 2 ...
-1
votes
1answer
551 views

Tuning JavaVM on AWS/EC2

there's some specific tuning JVM configuration for AmazonWS/EC2 building blocks (small, large...)? Somebody have suggestions for tuning JVM running on these machine profiles? Regards, And Past
1
vote
1answer
970 views

NGinx vs Varnish as a reverse proxy in front of Apache w/php [closed]

I am using apache with mod_php to serve content. Mostly the content is fetched form memcache over the network. All of my images, css and js are already on a cdn What are the pros and cons of putting ...
0
votes
2answers
97 views

Server configurations for hosting MySQL database

I have a web application which uses a MySQL database hosted on a virtual server. I've been using this server when I started the application and when the database was really small. Now it has grown and ...
1
vote
2answers
247 views

I'm seeing performance problems with postfix accepting mail when the queue is already large, any suggestions?

I use postfix to do final delivery for a mail system I've written. So this postfix installation only accepts mail from me, and bounces. When the postfix queue is empty, it can accept a piece of mail ...
0
votes
1answer
822 views

Oracle Application Server Performance Monitoring and Tuning (CPU load high)

Oracle Application Server Performance Monitoring and Tuning (CPU load high) i have just hired by a company and my boss give me a performance issue to solve as soon as possible. I don't have any ...
3
votes
3answers
510 views

httperf hangs when using --hog

I'm using httperf from a large ec2 instance with ubuntu 10.04 (no other software installed). When I test without --hog the tests run however when I use --hog the tests never end
3
votes
2answers
361 views

Tuning MySQL and Linux to reduce maximum response time specifically

We have a MySQL-based application that is very response time sensitive. A MySQL stored procedure needs to respond on average in less than 10 milliseconds and the maximum acceptable response time is 50 ...
4
votes
1answer
496 views

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. ...
0
votes
1answer
244 views

Windows 2003 IIS webserver (testserver) is slow

I have a test environment for my Asp.Net 4.0 web applications. It runs on a Dedicated Windows 2003 Webserver (IIS 6) But it's slow! The machine never has 100% cpu and the same for memory. When I run ...
2
votes
2answers
1k views

Apache with prefork model using 1000 MB memory per process

I am currently working on a site which uses Apache running on the prefork memory model. The following is the configuration from httpd.conf <IfModule prefork.c> StartServers 30 ...
0
votes
1answer
576 views

Improving TCP performance over a network with small packet loss

I’m trying to improve my TCP throughput over a “high delay network”, with some packet drops, between Linux machines. I set tcp_mem, tcp_wmem and tcp_rmem to “8192 20530752 20530752”. I set rmem_max, ...
13
votes
3answers
2k views

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 ...
1
vote
1answer
676 views

How Do I Troubleshoot Exim Mail Retry Issues?

My server is encountering high CPU load (like almost pegged at 100%) so much that the Apache service can't run and we get Apache 500 errors. We used a script to catch this and this is where we ...
1
vote
1answer
1k views

Windows Server 2008 File Server Performance Tuning

I am running a Microsoft Windows Server 2008 R2 File Server on our network. It seems that there are many times where accessing the data from the server is really slow, sluggish, or non-responsive. ...
6
votes
2answers
2k views

what does locked % in mongostat mean?

When running mongostat to look at our mongo database, I'll frequently see the locked % number jump up, sometimes as high as 80%. Here's a few example rows: insert query update delete getmore ...
0
votes
1answer
368 views

Trim out useless apache modules

I'm running a shared hosting environment with about 100 sites - I just took a peek at all the modules apache is loading/using, some of these I don't know what they are or do or if they are useful at ...
0
votes
1answer
699 views

Increase bandwidth of Linksys WRT54GL (with Tomato inside)

I have Linksys WRT54GL with Tomato firmware installed. When I connect internet cable directly to a computer I can download at about 8 MB/s, however when internet is access through the router maximum ...
0
votes
3answers
1k views

Increasing Postfix Performance for Outbound Mail

We're trying to optimize a Dell PowerEdge 1850, Dual 3GHz procs, 3072MB RAM, running Postfix 2.8.4 and signing mail with OpenDKIM 2.4.1. iostat -x output is: avg-cpu: %user %nice %system %iowait ...
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votes
1answer
211 views

Linux script to check settings and recommend tuning changes? [closed]

I'm searching for a script to run on our linux server and recommend various tuning changes we might consider making, as well as their suggested values for consideration. Any ideas if something like ...
0
votes
4answers
1k views

How to check for bottlenecks in Windows Server 2008 R2

I recently switched out a 10 year old server for a brand new server in a small office and upgraded from Windows Server 2000 to Windows Server 2008 R2. After the switch was complete and some ...
0
votes
3answers
1k views

How to speed up apache

We have a server with 8Cores, 16GB of RAM and RAID 0 SAS 10K drives. Our goal is to use this to serve a fairly simple php application quickly. We have tested all other components and we think we have ...
1
vote
2answers
168 views

SQL performance, how to exactly measure bottlenecks

Yesterday me (programmer) and one of my coworkers from our Hosting department started series of tests to address performance issues with our websites. We are running a server with Windows Server 2008 ...