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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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 ...
Oleg Vazhnev's user avatar
3 votes
2 answers
15k views

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 ...
Oleg Vazhnev's user avatar
0 votes
1 answer
921 views

epoll timeout configuration in lighttpd

Is there a configuration option to tune epoll timeout in lighttpd? I'm developing an embedded Linux (2.6) device, with lighttpd 1.4.30. And I'm observing the following issue: even when the system is ...
alexa's user avatar
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Before buying it, how can I tell if a storage array makes certain performance counters available over SNMP?

I've noticed that documentation for SNMP reporting that is built-in to devices (i.e. doesn't need an agent running in an OS) usually doesn't include a list of performance counters that are available ...
alx9r's user avatar
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How do I increase UDP Recv-Q

I have a gigabit connection that is not fully utilized but I am getting packet receiving loss. When I do netstat, it shows the Recv-Q sometimes maxes out at 262656 during heavy traffic. Proto Recv-Q ...
user169546's user avatar
2 votes
1 answer
1k views

Apache high CPU usage, setting a overload limit

On a ubuntu server, I run a LAMP environment with APC, and fast-cgi as php mod, to host 2 wordpress sites, and both sites have Wordpress Total Cache (W3TC) plugin configured. The server's specs are: ...
w0rldart's user avatar
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11 votes
3 answers
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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 ...
nn4l's user avatar
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Why am I getting a Sudden Drop in throughput and sluggishness with no CPU increase

Occasionally, during random parts of the day, I get a 10 minute period of extreme sluggishness where my requests are taking 50-1000 times longer then they normally do. Note: I am on Apache/2.2.16 (...
Pascal Aschwanden's user avatar
0 votes
2 answers
2k views

virtual memory optimization on exchange server 2010

Hi I did some Google searching but came up blank I know mycomputer/computer > Properties > advance System settings > Advance[tab] > Settings[Performance] > Advance [Tab] > Change > customsige ...
zman's user avatar
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4 votes
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TCP tunning for ssh port forwarding [closed]

I am using an ubuntu openssh server to allow users to connect to and do dynamic port forwarding. the performance is good until about 100 users are connected. beyond that the performance is dropped too ...
john melkon's user avatar
15 votes
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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 ...
NeilB's user avatar
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2 answers
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Changing memory allocator to Jemalloc Centos 6

After reading this blog post about the impact of memory allocators like jemalloc on highly threaded applications, I wanted to test things on a larger scale on some of our cluster of servers. We run ...
Brian Lovett's user avatar
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1 answer
3k views

Varnish: Exclude section of page

Is there any way to exclude some webpage parts from cache? For example, I have Recent Additions block on my homepage which gets refreshed after every 15mins. I know there is something like ESI ...
Sukhjinder Singh's user avatar
2 votes
1 answer
11k views

Apache HTTPD configuration for high load [duplicate]

Good day, I want to be able to serve at least 7000 (preferably 10k) concurrent requests from my Apache Httpd. I have configured my httpd.conf with MPM worker with the following setup ServerLimit ...
Franz See's user avatar
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4 votes
3 answers
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Manage Win7 Performance Options via GPO

Our company has many virtual Windows 7 instances. Based on recommendations from VMWare, we want to customize the visual effects to optimize performance. We have found that we can change the following ...
Kevin Shoaf's user avatar
1 vote
2 answers
758 views

Visualize overloaded nic in linux (kernel time)?

I have a linux server that keeps getting its NIC overloaded and I need to visualize how and why this is occurring based on connections and CPU utilization. How do I do this? For example; for me to ...
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1 answer
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Copying cause big iowait

I have dedicated server with 3 HDD. System disk, backup disk (same as system disk) and data disk. When I copy lot of data with cp (say, between backup disk and data disk) load average goes sky high. ...
Vald's user avatar
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4 votes
3 answers
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Disk write speed much slower than read speed

I have a VPS server (WiredTree), running CentOS. After experiencing some performance issues I created a simple benchmark for disk read/write speed using the following script: echo Write to disk dd ...
yby's user avatar
  • 175
6 votes
1 answer
12k views

Strange high CPU I/O wait on postgresql server

I'm really struggling with a performance issue currently, where all my database queries takes up to a 1000 times more than normally, when my database server is under "heavy" load. I have a server ...
Niels Kristian's user avatar
0 votes
1 answer
991 views

High response time with pingdom

I have a server hosted at my end, I am monitoring the server with pingdom and also my router. Strange thing is the response time towards the router is fine, but when the traffic flows towards the ...
kirac's user avatar
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1 vote
6 answers
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How to know if my nginx is in good health?

I am running a nginx on EC2 (m1.small) for SSL termination. I am using 2 workers on Ubuntu, with latest nginx (stable), the network throughput is around 2Mbps and system load average is around 2 to 3....
Howard's user avatar
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6 votes
1 answer
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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....
Tux's user avatar
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-2 votes
1 answer
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Which will give more free RAM to linux? [closed]

Trying to avoid some issues so I've been trying to learn vm. in kernel tuning but still a little confused even after googling. The lower background_ratio is the sooner the flushes? the lower ...
Linda Thomas's user avatar
1 vote
1 answer
2k views

VM Tuning to enhance performance

vm.bdflush = 100 1200 128 512 15 5000 500 1884 2 vm.dirty_ratio = 20 vm.dirty_background_ratio = 10 vm.swappiness = 10 vm.min_free_kbytes = 300000 That means that the MOST dirty data that can be in ...
Tiffany Walker's user avatar
2 votes
0 answers
264 views

Getting the virtual memory address for (major) page faults

On a Linux (Cent OS 5) system, I have a process that accesses a large amount of memory mapped files. The process is generating a large amount of page faults because the aggregated size of the mapped ...
VoidPointer's user avatar
0 votes
1 answer
264 views

Adding varnish and memcached to an running single server web site

Current set up; I have a single dedicated server running a web site (it's a lamp stack forum) OS : CentOS CPU : Dual 3.2Ghz Quad-core Xeons RAM : 40GBs (10x4GB DIMMs) Storage : Software RAID1 with ...
Baldrick's user avatar
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-5 votes
1 answer
1k views

CFQ vs Deadline - performance benefits [closed]

Running CPanel and wondering what would be the best for web hosting? deadline is more balanced over CFQ right so would allow for more I/O activities right
Julia Roberts's user avatar
3 votes
1 answer
7k views

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/...
Tiffany Walker's user avatar
12 votes
3 answers
17k views

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. ...
Alexander Gladysh's user avatar
5 votes
2 answers
2k views

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 ...
Alexander Gladysh's user avatar
0 votes
1 answer
231 views

MySQL Threads or what is this

How can I reduce that number? I have a quad core machine. Do I need to edit thread_pool_size and by reducing them do I get better performance? Should a lot of queries or something happen could is ...
Julia Roberts's user avatar
2 votes
2 answers
2k views

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 ...
Alexander Gladysh's user avatar
0 votes
1 answer
341 views

503 error Varnish cache when eAccelerator is started

I have a Magento installation running on x-large Amazon server. I have Varnish, memcached and eAccelerator installed on the server. At first everything was working fine, but then at some point it ...
srgb's user avatar
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1 vote
1 answer
2k views

How do change the max IO request size on Windows Server 2008 R2

As I understand it Windows Server 2008 R2 has the ability to send IO requests to the storage subsystem of up to 1MB in size. Back in the Server 2003 era (and before) this used to be limited to 64KB. ...
davefiddes's user avatar
1 vote
1 answer
5k views

JVM tuning in JBOSS AS 7

Can anyone explain as to where and how do I configure the following JVM parameters to tune JBOSS. I am using the latest JBOSS AS 7. I am using openJDK-6 on Linux. The following are the parameters ...
Prakash K's user avatar
  • 139
1 vote
1 answer
587 views

RRAS (Routing and Remote Access) change process priority to "realtime"?

I have a windows server 2012 running RRAS and some other services. Beacause of that I guess I have experience some slowdowns and dropout of package. My question is how to find, and change the ...
Illeman's user avatar
  • 23
-1 votes
1 answer
1k views

MySQL runs at >=100% CPU, heavy disk I/O?

Recently my Debian Linux server has been experiencing slow web server response times. I've investigated and it seems that MySQL is the culprit, yet there are no slow queries indicated by the slow ...
Nick's user avatar
  • 99
1 vote
1 answer
1k views

Doubled up RAM to 32 GB - now how to speed up a "LAPP" server?

I run a small Facebook game at a CentOS 6.3 quad core machine with PostgreSQL 8.4.3 + few PHP scripts (doing mostly select queries) + 1 Perl daemon and even though the server worked ok, I've suggested ...
Alexander Farber's user avatar
3 votes
3 answers
9k views

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 ...
ntherning's user avatar
  • 265
5 votes
1 answer
4k views

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 ...
Justin's user avatar
  • 303
2 votes
1 answer
106 views

Server hanging when serving random file on page load

I'm optimising a website, and the problem I'm facing with now is server related. During page load, there are about 40-50 requests sent to server (depending on the page), and in every case, server ...
srgb's user avatar
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2 votes
1 answer
2k views

Different block sizes for partition and underlying logical disk on HP Raid Controller (Linux)

Following links collected in this thread I started to check blockdev and found the following output indicating different sizes for partition c0d9p1 and the underlying device (c0d9): [root@machine ~]# ...
Wawrzek's user avatar
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1 vote
0 answers
442 views

Can I tune my Debian KVM server to benefit my Windows guest?

Debian Squeeze KVM server with Win2k8 server guest. The server has 16GBs of RAM and the guest only runs MS SQL, with a 15GB database on it. I am wondering if there is anything I can tune from the ...
Baldrick's user avatar
  • 4,242
0 votes
1 answer
1k views

Perfmon - Redirector current command 0 result

I'd like to monitor how many SMB connections there are at any given time for my 2008R2 file server, but when I add Redirector/Current Commands in perfmon, I get 0 results. This KB from Microsoft isn't ...
Dave's user avatar
  • 367
6 votes
1 answer
216 views

How to prevent IO Load under Linux for Video serving?

I'm currently serving videos of conferences via Nginx on 3 servers; 4 cores, enough memory (no swap used) and RAID-10 with 8 drives per server. Unfortunately iostat -xd 1 gives me 100% on all 3 ...
CharlesS's user avatar
  • 228
9 votes
4 answers
77k views

How to achieve 500K requests per second on my webserver? [closed]

I recently gifted myself a new dedicated server and I am trying to squeeze maximum performance out of it, for fun and learning. I am trying to achieve maximum possible requests per second this server ...
Arpit Tambi's user avatar
18 votes
9 answers
69k 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 ...
john titus's user avatar
0 votes
1 answer
513 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 ...
marcoc's user avatar
  • 748
0 votes
4 answers
1k 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 ...
Frederik's user avatar
  • 3,387
0 votes
2 answers
65 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 ...
Sabya's user avatar
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