Questions tagged [performance]
Questions about server hardware and software performance, or network performance.
3,202
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Measure & benchmark the speed & latency of file access on a mounted NFS share
I have a Linux Centos system that mounts some NFS shares, what technique can I use to measure the I/O speed/latency/rate when reading and writing files from that share? Could this technique also be ...
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2
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How are CPU time and CPU usage the same?
In the Wikipedia page for CPU time, it says
The CPU time is measured in clock ticks or seconds. Often, it is
useful to measure CPU time as a percentage of the CPU's capacity,
which is called ...
- 2,590
28
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High disk I/O - jbd2/sda2-8 process
I have run a file server on a CentOS 5.8 final server.
My only concern at the moment is what appears to be intermittent but continuous high disk I/O activity causing a general slowdown because of ...
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4
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Is it reasonable to use NFS on a production web server?
Can NFS be reasonably used on production servers as a means of connecting a compute server to a storage server, assuming the connection is over a LAN 1Gbe or 10Gbe connection?
There's obviously some ...
- 371
26
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8
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How can I disable encryption on openssh?
I'm having performance problems using openssh (server) and putty (client) combination to use a remote webproxy. I'd like to disable encryption and test the results to see if it makes a difference. How ...
Mark
26
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11
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Are there any good reasons for disabling hardware-assisted virtualization?
We've had a number of servers from Dell recently, all of which have had hardware-assisted virtualization disabled in the BIOS.
As far as I know hardware-assisted virtualization is a good thing - so ...
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3
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How much overhead does x86/x64 virtualization have?
How much overhead does x86/x64 virtualization (I'll probably be using VirtualBox, possbly VMWare, definitely not paravirtualization) have for each of the following operations a Win64 host and Linux64 ...
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26
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4
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How to pick between RabbitMQ and ZeroMQ or something else?
I'm looking for a queuing system which is fast and reliable and potentially can be spread across machines. Platform is Linux. Open source is preferable.
Both RabbitMQ and ZeroMQ look good but I ...
- 1,137
26
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4
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NFS poor write performance
I have two machines connected with 10Gbit Ethernet. Let one of them be NFS server and another will be NFs client.
Testing network speed over TCP with iperf shows ~9.8 Gbit/s throughput in both ...
- 611
25
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5
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Can a pool of memcache daemons be used to share sessions more efficiently?
We are moving from a 1 webserver setup to a two webserver setup and I need to start sharing PHP sessions between the two load balanced machines. We already have memcached installed (and started) and ...
- 4,367
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8
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Should I completely turn off swap for linux webserver?
Recently my friend told me that it is a good idea to turn off swap on linux webservers with enough memory. My server has 12 GB and currently uses 4GB (not counting cache and buffers) under peak load.
...
- 1,309
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How many files in a directory is too many? (Downloading data from net)
Greetings,
I'm writing some scripts to process images from various photo websites. Right now I'm storing all this data in individual text files in the same directory.
The directory is web ...
- 535
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9
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What impact does full hard drive encryption have on performance?
We have HP notebooks here at work, and it is policy to have HP's hard drive encryption turned on to protect client databases and IP in the case of loss/theft.
I was wondering if there was any ...
- 755
23
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1
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How to describe VMware performance requirements for our application to a VMware admin?
Often, an installation of our on-site, debian-stable based application runs in a virtual machine - typically in VMware ESXi. In the general case we do not have visibility into or influence over their ...
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8
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Analyzing Linux NFS server performance
I'd like to do some analysis of our NFS server to help track down potential bottlenecks in our applications. The server is running SUSE Enterprise Linux 10.
The kind of things I'm looking to know are:...
- 12.3k
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Doing an rm -rf on a massive directory tree takes hours
We're using rsnapshot for backups. It keeps lots of snapshots of the backuped up file, but it does delete old ones. This is good. However it's taking about 7 hours to do a rm -rf on a massive ...
- 32.3k
22
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Best MySQL cache settings for 8gb RAM dedicated MySQL server using only InnoDB (5gb database)
I'm a pretty big noob when it comes to setting up MySQL for performance. And honestly I'm not worried about the fine tuning to squeeze every last bit of performance out of MySQL, but I do know that ...
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4
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Why would a heavily disk intensive application run faster on a SAN than on a Physical Disk?
Why would a heavily disk intensive application run faster on a SAN than on a Physical Disk? I would have expected the Physical disk to be slightly faster but in fact the process ran 100 times faster ...
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1
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Determining which process is causing heavy disk I/O?
I've seen this question:
How to identify heavy write to disk?
And I've used dstat and atop before...but they don't seem to pinpoint what process is causing disk I/O. For example, from dstat:
dstat ...
- 1,729
21
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7
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Troubleshooting a "slow" network
We've all had a complaint that the "network" is "slow" at some point: might be localized to one room (switch) or one computer, might just be Internet (DNS? Browser issue?), might be just one ...
21
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2
answers
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jbd2/dm-0-8 consuming all I/O
What is jbd2/dm-0-8 and why It is consuming all my I/O usage and causing I/O wait?
Is there anyway to disable this?
Bonnie++ results: http://pastebin.com/iQCWP1qp
$ sudo hdparm -t /dev/sda1
/dev/...
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What is the best filesystem for insert performance on PostgreSQL?
I'm curious if anyone out there has done any experimentation or comparisons between file systems and database performance. On Linux, I'm wondering what is the optimal file system for a postgres ...
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1
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Why higher await time for DM multipath device than underlying device?
We have a CentOS 6.4 based server attached to Hitachi HNAS 3080 storage and observed the kernel remount the filesystem in read-only mode:
May 16 07:31:03 GNS3-SRV-CMP-001 kernel: [1259725.675814] ...
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5
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Extremely fast booting server
I'm changing the way that our DHCP/DNS stuff works at work. Currently we've got 3 DNS servers, and a DHCP box. All of them are VMs.
There's a circular dependency where stuff booting requires NFS, ...
- 27.6k
19
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3
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How fast is MySQL replication?
I'm considering setting up replication of our mysql db to be able to have local slaves in each of our branch offices, while having the master in the main office to improve application performance (...
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1
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Apache 2.2 mpm_worker: more threads or more processes?
When using the Worker MPM in Apache, you can fiddle with the number of child processes and the number of server threads per child process.
What are the advantages and disadvantages of each? Under ...
- 6,858
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7
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Slow NFS transfer performance of small files
I'm using Openfiler 2.3 on an HP ML370 G5, Smart Array P400, SAS disks combined using RAID 1+0.
I set up an NFS share from ext3 partition using Openfiler's web based configuration, and I succeeded to ...
- 1,643
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Is running permanently in a VMWare snapshot bad for performance?
I understand that the VMWare KB frowns upon long running snapshots mainly due to two things (In my opinion)
Taking tons of snapshots can fill up the data store. Snapshots are simply delta files. ...
18
votes
10
answers
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How do I benchmark performance of external DNS lookups?
I'm considering Google's public DNS servers as the external DNS for my network. Currently I'm using the DNS servers from my ISP. I've also considered OpenDNS in the past, but ultimately decided not ...
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DRBD terrible sync performance on 10GigE
I've set up a pair of identical servers with RAID arrays (8 cores, 16GB RAM, 12x2 TB RAID6), 3 10GigE interfaces, to host some highly available services.
The systems are currently running Debian 7.9 ...
- 6,998
18
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591
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Vendor whitepaper says: 5Mpps no prob. I'm already hitting a wall at 120kpps. Where's the bottleneck?
HP's whitepaper on their QLogic (fka Broadcom) NetXtreme II adapters, which includes the specific NIC that I'm testing, states (page 7) that their small packet performance for packets up to 256 bytes/...
18
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3
answers
16k
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Suddenly slow RAID performance
We recently noticed our database queries have been taking much longer than usual to run. After some investigation, it looks like we're getting very slow disk reads.
We've run into a similar problem ...
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18
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3
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GlusterFS vs Ceph, which is better for production use for the moment? [closed]
I am evaluating GlusterFS and Ceph, seems Gluster is FUSE based which means it may be not as fast as Ceph. But looks like Gluster got a very friendly control panel and is ease to use.
Ceph was ...
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3
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Measure Linux IOPS for a running system
How do I measure IOPS of a running Linux server? I know that the theoretical IOPS of a SATA drive is around 90 and enterprise 10k SAS/FC disk is 180. I want to know how much my running system is using ...
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8
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How to scale php5+MySQL above 200 requests/second?
I am tweaking my homepage for performance, currently it handles about 200 requests/second on 3.14.by which eats 6 SQL queries, and 20 req/second on 3.14.by/forum which is phpBB forum.
Strangely ...
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ext4 listing of files very slow in one specific directory that contained lots of files before
Background
I had a small logrotate misshap... Logrotate would rotate the archived logs by misstake causing a quadratic growth of files in my /var/log/. And by the time I caught wind that something ...
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2
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How do you disable the "last accessed" attribute on NTFS/Windows?
Inspired by this answer, I realize I have no idea how to disable the last accessed attribute in Windows to increase performance. If you can, how?
I know in Linux you can mount the partition with the '...
- 3,362
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3
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Why is Apache running so many processes? Excessive RAM here?
I notice Apache is running multiple processes on my LAMP server (ubuntu 10.10). I'm just running a Wordpress site with MySQL as a database. It seems like www-data is running apache2 more than it ...
- 959
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9
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How do I profile MySQL?
What tools exist to profile MySQL, like how MSSQL 2000+ does with the SQL Profiler?
I'd want to trace things like SQL statements executed, execution times, execution plan, etc.
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IO Wait causing so much slowdown (EXT4 JDB2 at 99% IO ) During Mysql Commit
I am writing an indexer, using python, which indexes documents and insert them into Database, Before it was single process but now i made it to multiprocessing with 4 parallel processes running.After ...
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Can a virtualized machine have the CPU and RAM resources of multiple underlying physical machines?
We are studying implementing some virtualized servers here, but we don't know what will be better suitable for us. Some folks are saying better have two huge servers, and others are saying have like a ...
- 295
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14
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Why would wireless routers become less reliable over time?
I've been curious about this for awhile now. I don't know if I'm seeing a real pattern or not, but having worked with many home office/small office wireless routers for a few years now, I've noticed ...
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6
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How to improve MySQL INSERT and UPDATE performance?
This question can probably be asked on StackOverflow as well, but I'll try here first...
Performance of INSERT and UPDATE statements in our database seems to be degrading and causing poor performance ...
- 1,314
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votes
4
answers
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Performance difference between compiled and binary linux distributions/packages
I was searching a lot on the internet and couldn't find an exact answer.
There are distros like Gentoo (or FreeBSD) which does not come with binaries but only with source code for packages (ports).
...
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1
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What's the difference between a "degraded" RAID 6 array and a "clean" RAID 5 array?
Suppose you have two RAID arrays, one with N disks and one with N+1 disks. The array with N disks was formatted as a RAID 5 and left alone, while the other array was formatted as a RAID 6 before one ...
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1
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Why is my rsync so slow compared to pure cp or even scp?
I'm transfering the files from Linux to Windows 7 via a mounted share (the share is mounted from Windows on Linux).. I'm copying lots of data (i.e. nearly a TB) from the old to the new machine within ...
- 1,526
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How to troubleshoot latency between 2 linux hosts
The latency between 2 linux hosts is about .23ms. They are connected by one switch. Ping & Wireshark confirm the latency number.
But, i dont have any visibility into what is causing this latency. ...
- 303
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5
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14k
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How can I replay Apache access logs back at my servers to do real world load testing?
I looked at Tools for load-testing HTTP servers? but I couldn't see how to replay my own existing logs in any of those tools. I have a bug that only occurs under certain load operations which my ...
- 1,155
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How to identify the cause of 100% CPU usage in Azure App Service?
I have five apps in an Azure App Service Plan, all different copies of the same app for different clients. It's an ASP.NET MVC app with an SQL database.
This morning I woke up to slow and non-...
- 311
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11
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Would rebooting the server in a schedule be good idea for performance?
I am wondering if rebooting a server in a schedule would be good idea for performance.
Let's say we want to reboot the server at 02:00 AM per 2 nights.
The server here is Windows Server 2008 R2. ...
- 935