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

learn more… | top users | synonyms

4
votes
4answers
1k views

MySQL taking too much CPU

Below is my .cnf file and if I see my CPU consumption 99.99% of it my the mysqld commands. The MySQL server is connected from remote machines that update data in it frequently, but I make sure that ...
7
votes
1answer
200 views

What do users see when Apache reaches MaxClients?

Occasionally, in my Apache error log, I will find: [error] server reached MaxClients setting, consider raising the MaxClients setting I've purposely lowered MaxClients in the past (to 60) due to ...
0
votes
1answer
70 views

Does Apache mod_status give any insight to tuning Apache config?

Does the Apache mod_status output give any insight to tuning Apache prefork config? For example, using Apache's mod_status, I figured out that My server gets 3 requests/sec average, the range is ...
2
votes
1answer
231 views

NFS performs ways worse than SSHFS, how can I debug?

Situation: zfs server over 10GbE p2p at 192.168.201.1 running omnios, debian client at 192.168.201.2. The nfs performs fairly well on big files but horribly slow on small ones. For instance, cp -r ...
0
votes
1answer
259 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 ...
0
votes
1answer
135 views

How to diagnose Nginx bottlenecks at specific number of users

Firstly, I know this is a loaded question, but I hoping that you guys will be able to point me in the right direction.... We've got a number of nginx-fronted web heads which site behind an AWS ELB. ...
1
vote
1answer
3k views

Slow performance due to txg_sync for ZFS 0.6.3 on Ubuntu 14.04

I am using native ZFS with "ZFS on Linux" installed from the PPA here. Setup was not a problem and I am using it in mirrored configuration with two WD 4TB Red HDDs. Unfortunately I am having ...
1
vote
0answers
99 views

Multipath tcp application level performance measurement

I am working on a project related to Multipath tcp and I want to measure the goodput and the RTT at the application level. I don't want to use a traditional tool(netperf, iperf, ...) and I want to ...
1
vote
2answers
2k views

Optimize Apache for EC2 micro instance

I'm running apache2 on a EC2 micro instance with ~600 mb RAM. The instance was running for almost a year without problems, but in the last weeks it just keeps crashing, because the server reached ...
0
votes
0answers
27 views

How to measure file access by process over time?

I would like to take a sampling of data / file access over the course of several hours or days in order to ascertain what processes (with their accompanying files) are consuming the most drive IO in ...
2
votes
2answers
2k views

Configure HAProxy on Linux to accept 10K simultaneous connections

I have HAProxy 1.5 running on Ubuntu 14.04 (modified). It accepts connections on http and https ports. Two backend applications process requests using persistent connection. When I create around 2200 ...
0
votes
0answers
29 views

How to ascertain where to effectively allocate server resources?

I have recently received an upgrade to one of my servers of a 256GB SSD drive (this is in addition to two other primary 1TB drives) and a memory upgrade bringing the server to 64GB from 32GB of RAM. ...
7
votes
5answers
5k views

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 ...
1
vote
0answers
153 views

Performance issues with cross-drive NTFS junctions

I have the following setup: Windows 8.1 32-bit Drive 0: system drive, SSD, NTFS, mounted at C:\ Drive 1: data drive, magnetic HDD, NTFS, mounted at C:\Users\Database User\Documents and Z:\ ...
0
votes
2answers
332 views

increase nginx active connection more than 65535

currently I'm doing setup for nginx to accept C1M, I do in my Virtual BOX with Centos 7.0 and RAM 10G. Here my sysctl.conf configuration. fs.file-max = 9999999 fs.nr_open ...
0
votes
1answer
96 views

Seeking advice on performance metrics based on NewRelic dashboard

Some background: I have been given access to our newrelic dashboard for the production servers running a django app on an AWS account, and tasked to come up with some gatling.io (performance testing ...
-1
votes
1answer
254 views

measuring network throughput with netperf

I'm doing benchmark test of Linux server using netperf. According to information at networksecuritytoolkit the theoretical max throughput rate for 1514-bytes packets is 117.35 Mbp/s. However I'm ...
2
votes
1answer
517 views

BTRFS, sector alignment and Advance Format Disks

I want to set up a BTRFS RAID1 setup with two WD Red 4TB disks, which possess 4K sectors. Since I am keen to get it right the first time before copying data to it (yes it will be backed up), my ...
0
votes
1answer
771 views

Tuning Apache KeepAlive Timeout for HTTPS

My website forces HTTPS everywhere and has an average first load time of 3-5 seconds. Thanks to caching, repeat load time is 0.8 seconds. The SSL negotiation takes 150-300ms on my server, so I want ...
1
vote
1answer
1k 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. ...
3
votes
1answer
2k views

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? ...
2
votes
1answer
138 views

Data Transfer Speed Hardware Config

First off, I am sorry if this gets a little scattered, it encompasses a large problem for me I have been dealing with for some time. Here is a little background: I operate an educational website ...
1
vote
1answer
262 views

Tuning Linux TCP for large number of TIME_WAIT

It looks like we have a bunch of tcp connections hanging around on a busy webserver, this is the output from ss -s: Total: 366 (kernel 1037) TCP: 72108 (estab 130, closed 71964, orphaned 0, synrecv ...
0
votes
0answers
2k views

Apache Worker MPM / PHP-FPM Tuning

I have a VPS running CentOS 6.5, Apache 2.2, PHP-FPM v5.4 and MySQL 5.5. I take advantage of APC and Memcache. The VPS has 8 cores and 8GB RAM. I'm running a medium volume site (15,000 users / day, ...
2
votes
1answer
280 views

Will noatime on a tmpfs volume improve performance?

I am using /run/shm/myfolder for nginx micro caching, also keeping ngx_pagespeed files there. I am wondering if there will be a speed increase if I go from relatime to noatime? It's for HDD, but on a ...
2
votes
3answers
2k views

Can tail slow down log writing speed on Linux (ext3)?

I'm wondering if tailf can generate blocking I/O which will slow down server responsiveness due to logging. For ex. assuming the following setup: Debian 5.1 linux server (foo) which is managed via ...
1
vote
1answer
1k views

Apache Start Servers, Min/Max Spare Servers Ram Consumption Influence

I have a 1gb ram VPS. If I stop apache I have 400 mb ram free. So the max clients should be (total ram - used ram) / max_service_ram_consumption = 400 / 31. So MaxClients should be 13. These are the ...
0
votes
1answer
222 views

How can i speed up an XWiki installation on debian?

We installed XWiki on Debian. Page load times in default config were about 2 seconds. Tuning the memory parameters according to the XWiki performanve guide brought it down to 1 second. But for a local ...
0
votes
1answer
76 views

Negative effects of setting nginx workers too high

I've seen numerous posts advising how to set nginx's worker_processes, but very few detailing what happens when this is set too high. I'm about to run some benchmarks, but I'd appreciate advice on ...
2
votes
2answers
215 views

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 ...
1
vote
3answers
802 views

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 ...
0
votes
2answers
156 views

How to tune a web server and prep it for lots simultaneous visitors?

I have another related question but I'm deviating from it since I'm changing my server to use nginx instead of Apache. Related: Server problems, running out of RAM, really high load average I'm ...
6
votes
3answers
8k views

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 ...
0
votes
1answer
51 views

TOP processes by system time

I have a system running 2 processes - MySQL and Java I'm seeing 20-30% of the time spent in %system. I've looked around to try and find a way to identify which what the balance of the system time is ...
3
votes
2answers
3k views

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 ...
4
votes
2answers
6k views

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. Network latency when ...
0
votes
0answers
366 views

Tunning nginx/php5-fpm : why low memory usage with 800 users?

I did optimize nginx with what I found on the internet My specs are 2 servers load balanced : Intel Xeon E5-1620v2 (4c/8t 3,7 GHz+/3,9 GHz+) 32 Go DDR3 ECC 1600MHz 3x 160Go SSD Intel DC S3500 SATA3 ...
-2
votes
2answers
473 views

Centos Server Recently slowed down significantly

I have Dedicated Server on 1and1 with RAM - 16 GB HD 1000GB CPU: Intel(R) Xeon(R) CPU E3-1270 v3 @ 3.50GHz, 4 cores Centos 6 Apache/2.2.15 PHP 5.3.3 Mysql I have a video sharing website (on ...
0
votes
2answers
212 views

MySQL performance problems on particular vhosts

I have a dedicated server setup (8 cores, 16 GB of RAM), running Ubuntu 12.04 LTS with latest updates, and I am experiencing some performance problems related to MySQL. I have multiple vhosts active. ...
0
votes
1answer
44 views

How to alleviate high disk reads on server?

We are currently hosting a 3TB library of image galleries on our web server, all searchable by users. With about 400 active users at a certain time on the website, our disk reads are pushing 100% I/O ...
3
votes
1answer
5k views

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 ...
3
votes
1answer
834 views

How to remove the pause during JBoss 5.1.0 GA boot between ProfileServiceBootstrap and AnnotationCreator?

I've managed to strip down my JBoss profile enough that it boots in 1.5 minutes. I started with the web profile and started pulling out stuff I didn't need. The bulk of my boot time can be seen here: ...
2
votes
1answer
95 views

What is the correct way to track and monitor Exchange DB replication “pressure” over time?

I want to determine if some databases are overloaded or unbalanced, and think that looking at the transaction logs created per database over time would tell me which DB is at risk of missing RPO ...
1
vote
5answers
2k 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 ...
0
votes
2answers
1k views

Linux : SSD performance tweaking queue

I've allready applied well known mountpoint options for ssd, enabled stuff in LVM for ssd optimisation as well. Now i've ran into a possible challenge. Would it be possible to gather information on ...
2
votes
1answer
388 views

Execute ps1 script when CPU threshold is meet

I'm looking for a function similar to Debug Diagnostics Collector. Where you can setup a performance (or any counter) trigger (eg. above 50% CPU over 50 seconds). Once condition of a trigger are ...
1
vote
1answer
266 views

4096 and 8192 block size read slower than write? by using lsi 9361-8i RAID10

is it possible that 1024 and 2048 block size read speed is faster than 4096 and 8192 block? I'm using lsi 9361-8i with RAID 10 , with 8 x Kingston E50 250G. result: 1024 = Write: 2,251 MB/s ...
1
vote
0answers
74 views

IRQ not handled by all CPUs

I have a problem about balancing irq. I took irq numbers from /etc/interrupts and assigned each irq to each of 24 CPUs as this tutorial says for i in {143..166};do cat /proc/irq/${i}/smp_affinity; ...
2
votes
0answers
320 views

famd/gamin timeout issue with courier-imap

I'm running a mail server for about 200 users with courier-imap on Debian 7. This server is running a linux kernel 2.6.38 inside a Xen guest having 2 cpu cores and 2 GB RAM. The server accept ...
1
vote
1answer
840 views

how to disable all caches types in mysql server in order to do performance testing for my queries

I'm using Mysql Server 5.6.15 and i have a huge database with many complex queries. it seems that when I run the query the first time it takes X amount of time. when I execute it again it takes ...