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

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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. I'...
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4k 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 ...
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215 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:\ ...
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118 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 ...
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309 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 ...
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663 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 ...
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4k 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 ...
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1answer
150 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 ...
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313 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 ...
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3k 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, ...
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379 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 ...
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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 ...
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83 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 ...
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2answers
270 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 ...
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170 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 ...
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390 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 ...
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3answers
908 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 ...
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299 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 ...
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1answer
900 views

Why is GlusterFS so slow here?

We've set up a mirroring pair of GlusterFS servers. No special tuning, whatever came "out of the box" with GlusterFS-3.5.1 in the official RHEL6 RPM, that's what we have. The cluster works, but the ...
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1answer
937 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 ...
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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? ...
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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 ...
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8k 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 ...
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424 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 ...
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3k 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 ...
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545 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 joomla)...
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229 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. ...
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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 ...
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1answer
111 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 ...
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112 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 ...
2
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1answer
457 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 ...
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297 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 ...
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3answers
3k views

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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75 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; ...
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384 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 ...
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1answer
1k 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 ...
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139 views

What's the bottle neck of server hit 100K request?

The following are two graph of my digital ocean vps instance handle load test request. 10K/s, The only different is the request file size, first is 10K, the second is 20K. Can any one point out the ...
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408 views

PHP Settings [pm.max_children, pm.start_servers, pm.min_spare_servers and pm.max_spare_servers]

In the midst of transferring a website from a GoDaddy shared server to an EC2 instance. Handling the traffic, which during peak times on a typical day is around 300 active visitors, has been ...
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1answer
104 views

Server load avg. hitting 16-20, but all resources under 90% usage?

As you can see in the image shared below, the server load peaked to almost 20 but the CPU, RAM, DISK IO and Network I/O remained well under their full capacity. My question is: 1). What caused the ...
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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 ...
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210 views

tuning apache for low ram low traffic server

I have a low end VPS server with 512megs of ram to host downloads of files (~10-25megs each). what is a good configuration for the following parameters in apache. I expect no more than 10 human users ...
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325 views

OpenSSL performance oddity

I've seen something odd regarding OpenSSL performance. This is the output of 'openssl speed aes-128-cbc' on a physical HP Bl460c Gen8 with dual E5-2680's running RHEL/OEL 6.4x64 and OpenSSL 1.0.0-...
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1answer
1k views

rmem_max more than rmem_default

I just installed centos 6.3 freshly and noticed the following: [root@localhost user1]# cat /etc/redhat-release CentOS release 6.3 (Final) [root@localhost user1]# [root@localhost user1]# cat /proc/...
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Ubuntu backup script kills performance

I run a nightly backup, which takes about 1 hour. During that the performance is bad as hell. It looks pretty much like this: # DB dump ionice -c 3 nice -n 20 mysqldump --skip-lock-tables --user=foo ...
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587 views

How to identify which MySQL queries take a lot of time?

My MySQL server is consuming a lot of memory. Memory footprint 1. Memory consumption in descending order (top 4) MySQL's memory consumption in particular - Why is there so many number of mysqld ...
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1k views

performance monitor in iis 7 to monitor which website is using most resources (asp.net)

I am using Windows Server 2008 R2 and IIS 7.5, and am hosting multiple websites on the same webserver. Is it possible to use Performance Monitor to know on average which website is using the most ...
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1answer
454 views

KVM Slow performance on XP Guest

The system is very slow to do anything, even browse a local folder, and CPU sits at 100% frequently. Guest is XP 32 bit. Host is Scientific Linux 6.2, Libvirt 0.10, Guest XP OS shows ACPI ...
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17k views

Improving OpenVPN Performance

I've been trying to improve my OpenVPN performance and this is my current setup: cat /etc/openvpn/server.conf port 443 #- port proto tcp #- protocol dev tun #tun-mtu 1500 tun-mtu-extra 32 #mssfix ...
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2answers
50 views

How to exclude requests from unwanted sources

Scenario: Client buys our analytics services and includes our analytics SDK in his mobile app. Users who download the app will start sending us lots of data. When the client stops paying for our ...
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175 views

ZFS Equivalent of lvdisplay snap_percent

I've been using LVM snapshots for backing up MySQL databases. FLUSH TABLES WITH READ LOCK is issued and then lvcreate --snapshot --size 4G etc. Because the database is live while the snapshot is ...