The speed at which a program runs

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33 views

Set the TCP window scaling option to 4 & the TCP window size to 65535 [on hold]

I want all TCP packet (linux system) to be sent with: TCP window scaling option set to: 4 TCP window size set to: 65535 (0xffff). How I can configure my linux system to do that?
2
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2answers
36 views

Make rsync move (not copy) files on local file system

Can I make rsync to move large amount of files instead of copying them when on local filesystem? I would like it to behave like improved mv command. I know about --remove-source-files option but ...
6
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2answers
66 views

Besides cache, what does the Linux kernel use significant amounts of memory for?

My computer feels really sluggish. According to free, I have only ~200M RAM left and more than a gigabyte had to be swapped out. I know that it is good if memory is used for caching but this looks ...
3
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0answers
21 views

How to generate graphs from lmbench results?

I need to use the lmbench benchmarking tool to get the system performance statistics. I am able to execute and run the results. In the results folder this is a MakeFile with this information # ...
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0answers
29 views

Linux desktop (Mint MATE) requires reboot every few days

Summary After a few days of uptime, my system starts getting slow. How can I determine the cause and fix it? Opening a Youtube video or some web-pages will freeze Firefox for an increasing amount of ...
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1answer
51 views

Understanding high load average with vmstat, mpstat, sar, and top

I am trying to understand the load average on my system when idle. Here are some results after the system has been running for a few hours, with almost nothing installed. vmstat root@arm:~# vmstat ...
5
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0answers
64 views

What is the IPsec bottleneck in Linux?

I am trying to compare the performance of several network security protocols between two hosts connected in Gigabit Ethernet. My goal here is to see if I can saturate my bandwidth, and if not, what ...
2
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0answers
18 views

JVM low-memory tuning

What command-line options would provide the lowest memory-footprint JVM, in OpenJDK, or possibly other JVMs (Linux/Debian)? I'm willing to disable JIT, live with slow or choppy garbage collection, ...
2
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2answers
42 views

Pipe Viewer - Progress monitor performance consequence

I am writing a batch script to sort through gigs and gigs of data. All of the data is text but the script will take a long long time to execute. I would like to give some visual indication that the ...
2
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1answer
121 views

Understanding why such a discrepancy in network transfer?

Summary: I can't understand a peculiar discrepancy in network transfer. Why is there such a discrepancy in syncing from one machine to the other and vice versa? Also: Given the maximum network ...
0
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1answer
32 views

Overhead when relocating a directory to a different file system using a symbolic link

I need to relocate some frequently accessed files to a different file system. The simplest way of doing this is to move the directory containing the files to the new file system and creating a ...
3
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2answers
48 views

How does one determine when a process or machine is IO bound?

I have a node.js process which writes to many different sqlite databases. Sqlite can handle only one concurrent write per database, which is fine since there will be only one write per database at a ...
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0answers
79 views

'nc' using ~100% CPU when transferring a FIFO file

On the server which is always connected I’m using this in a crontab: @reboot nc -k -l 1337 < /tmp/fifo.fifo On the client which is not always on the network or switched on I’m using this ...
1
vote
1answer
79 views

how to choose appropriate linux hardware - poor graphics performance

I can't believe I am asking this question here myself. Apologies if this is not the right place for this question. I've been using linux since 1996, SuSE version 4.1... And yet I am still not able ...
0
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1answer
158 views

Why Linux games are less performanced than Win 7?

I had Windows 7 x64 and now I have Ubuntu 14.04 on notebook HP 4535s. I expected games to be faster in Linux than on Windows because of fewer machine requirements. But it isn't so... E.g., games via ...
2
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3answers
72 views

Optimise a shell script / command to delete files

I'm running Magento and it doesn't clean up old session data, so I need to clean it up with a shell script / cronjob: 0,30 * * * * /usr/bin/find /var/www/magento/var/session -name 'sess_*' -type f ...
0
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1answer
24 views

Solaris prstat - definition of “recent” time used in percentages

The man page for prstat (on Solaris 10 in my case) notes that that CPU % output is the "percentage of recent CPU time". I am trying to understand in more depth what "recent" means in this context - is ...
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0answers
88 views

SEGFAULT error 4 in libX11 on another X display caused by War Thunder

I read tons of info about performance boosting for linux gaming. One of them is to run games on a separate X server. After hours of search and tries, I ended up with something "working" for most of ...
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1answer
95 views

Does dm-multipath schedule I/O?

I have a multipath device I'm interested in: [root@xxx dm-7]# multipath -ll mpathf mpathf (3600601609f013300227e5b5b3790e411) dm-7 DGC,VRAID size=3.0T features='1 queue_if_no_path' hwhandler='1 alua' ...
1
vote
1answer
66 views

AIX CPU usage - how to know how many CPUs running?

Over AIX 6.1 - I do see the following output, it says I have 16 Max Physical CPUs; but there are only 8 active - why is that? The system will use the remaining 8 if needed? Or are they disabled? # ...
4
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0answers
56 views

Fixing terrible performance when watching/reading video and writing video files to disk

I have had this issue for quite some time and tried many times to fix it on my own and it always fails. IP schedulers, ionice and things like that always yield no result. I even went and bought an ...
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0answers
54 views

Variations in Ubuntu 12.04 /usr/bin/time statistics

I have a command line tool which I run on Ubuntu 12.04.5 LTS. I need to calculate the cpu time for this program. I have been checking /usr/bin/time function. command: /usr/bin/time -v -a -o ...
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2answers
358 views

Optimizing logical sector size for physical sector size 4096 HDD

With many new hard drive disks the physical sector size is 4096. Would it be possible to make the system use a logical sector size of the same size, rather than the default logical sector size of 512? ...
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0answers
18 views

Using `perf` repeatedly with file input

perf can be used to analyze the performance of a program. Say you want to test the performance of a program prgrm, with input from a file, you can run: perf stat prgrm < inp.dat Now when you ...
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0answers
26 views

run netperf without IP address available

I have DPDK set up, with two NICs taken over by DPDK, i.e. the interfaces are not visible to userspace applications. Now, I need to run netperf/iperf to measure throughput performance of port-to-port ...
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0answers
28 views

netperf: run with no control connection

Trying to run netperf without setting up a control connection between netperf and netserver: client% netperf -N -H 10.0.0.2 ... netperf: send_omni: connect_data_socket failed: No route to ...
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2answers
66 views

How to make a filter more efficient

I've created a script to compare a list of users from a MSSQL database against a list of disabled AD users. The tool we use for AD authentication returns data in the following format (with plenty ...
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3answers
126 views

Can I make [ $(($1 % $check)) -ne 0 ]; be more performant and not be killed?

If have the following code which works for up to 13 (line 2) in a few seconds but when I try and do upper teens and 20 it gets killed after a couple of minutes. divisible_by () { for ((check=2; ...
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0answers
140 views

Virtualized Debian Jessie: slow booting / shutting down :(

I have a Debian 8 (Jessie), cat /proc/version says: Linux version 3.16.0-4-amd64 (debian-kernel@lists.debian.org) (gcc version 4.8.3 (Debian 4.8.3-16) ) #1 SMP Debian 3.16.7-ckt2-1 (2014-12-08) ...
2
votes
2answers
79 views

Why is userspace slower than the kernel?

I've heard that FUSE-based filesystems are notoriously slow because they are implemented in a userspace program. What is it about userspace that is slower than the kernel?
5
votes
2answers
43 views

How to find the number of bytes rewritten to a folder hierarchy?

I want metrics for how much writing and reading have been done to a folder. vmstat -d gives metrics at the whole disk level. iotop will give per process rw stats. But how can I find out how much ...
0
votes
1answer
62 views

Where is NMon cron job for AIX?

While trying to know where is NMon job configured to run; I do find that it's NOT listed on Crontab (using crontab -l). BUT - the job is currently running as expected, which is weird. See the ...
2
votes
0answers
30 views

Why does my fresh Debian have a high latency?

The time between clicking and seeing a response is very high. Typing looks very funny, and makes me feel queasy. I think there's about 50-20ms "extra". I would expect a top notch linux distro to have ...
3
votes
1answer
169 views

How does netstat command fit in various layers of TCP/IP model in the performance diagram?

netstat command is useful to, Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. Now, I was reading about the Linux performance ...
1
vote
1answer
72 views

Is it useful for a proxy to buffer less data than Linux RCVBUF can?

I am looking at how HTTP proxies and reverse proxies deal with slow client problems. The idea is that the upstream server only have a limited slots for clients and if the client is slow to receive ...
0
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0answers
252 views

Increasing ulimit stack size benefits?

Hello I'm new in Linux and at my work I have a server that runs a banking software. The company that made the software said that the stack size should be set to unlimited. Does this make the software ...
2
votes
1answer
36 views

Why is my computer sluggish after downloading a lot?

When I download a lot of data (e.g. 3GB) in one go, using a program such as Transmission or Wget, progressively during the downloading, and after it has has finished, the computer always seems ...
1
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0answers
60 views

How to diagnose CPU performance problems?

Recently I bought a new netbook based on AMD A4-1200 CPU and installed Linux Mint 17 with XFCE. RAM is 4GB So, testing some of my programs, I found very strange behavior. On random intervals, the ...
4
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2answers
248 views

Disk busy is close to 100% and iowait is 0,0% on SunOS, how can it be possible?

During monitoring of SunOS5.10 machine I noticed strange behavior: Disk busy is close to 100% Disk waiting time is 0,0% Primary purpose of this machine is running application server on jvm. This ...
16
votes
3answers
1k views

Why is coreutils sort slower than Python?

I wrote the following script to test the speed of Python's sort functionality: from sys import stdin, stdout lines = list(stdin) lines.sort() stdout.writelines(lines) I then compared this to the ...
2
votes
1answer
77 views

What could be done to make Embedded Linux boot faster?

My team is developing a software for a Embedded Linux solution. The problem we are facing is that it takes too much time for the system to be ready to start running our desired apps (that is, too much ...
0
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0answers
38 views

Xorg consumes CPU, RHEL 7 fresh install

I've installed RHEL 7 with default settings. I wonder why Xorg consumes 30% of my CPUs. How can I know what's wrong and how to fix it? HP DL360p Gen8, dual Xeon E5-2640
0
votes
1answer
98 views

rsync: Copy speed decreases while syncing two directories

I am using rsync on fedora 20 to sync my directories. I am using the command below:- $ rsync --progress -a srcDir DestDir But, as rsync copies files, copy speed decreases significantly. Here is my ...
1
vote
1answer
234 views

Find the process which is taking maximum CPU usage if CPU usage is more than 60%?

I am trying to measure the cpu usage of my ubuntu machine and if the cpu usage is more than 60%, then I need to find out the process who has the highest cpu usage and then send out an email saying CPU ...
1
vote
1answer
55 views

Disk is a bottleneck. Background processes make things worse. How to improve responsiveness?

Often, the bottleneck of my laptop is the disk. When doing some disk-intensive computations, automatically-started background processes like updatedb, find /something etc. kick in, making things even ...
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vote
3answers
68 views

Software RAID10 setup writes small files extremely slowly, is this normal?

I have a software RAID-10 setup on Linux 3.16.6-203.fc20.x86_64, with 1.2 metadata and the default chunk size (512K): $ cat /proc/mdstat md0 : active raid10 sdc1[4] sdb1[0] sdd1[2] sde1[3] ...
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0answers
54 views

Properly mount a windows share to move files on the mountpoint

This question resulted from a question of mine on stackexchange. I mount a windows share with mount -t cifs -o ...
8
votes
3answers
2k views

Transfering millions of files from one server to another

I have two servers. One of them has 15 million text files (about 40 GB). I am trying to transfer them to another server. I considered zipping them and transferring the archive. But I realized that ...
0
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1answer
68 views

Questions about CPU usage [closed]

How bad/normal/good is this CPU usage? Cpu0 : 14.4%us, 6.3%sy, 0.0%ni, 78.8%id, 0.0%wa, 0.0%hi, 0.5%si, 0.0%st Cpu1 : 88.3%us, 8.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 3.7%si, 0.0%st ...
0
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1answer
37 views

Why scp with compression takes longer than without compression

I was playing around and noticed that secure-copying with compression takes longer than without compression time scp -C ./test.sql user@vmware:/home/user real 0m42.758s user 0m40.455s sys ...