The speed at which a program runs

learn more… | top users | synonyms (1)

1
vote
0answers
18 views

Debian 8 performance problems with good hardware

I'm finally asking for help after some research, 'cause my problems are getting me crazy... I bought about 6 months ago a good laptop (Lenovo ThinkPad E550 : Intel Core i5-5200U, 8 GO DDR3, AMD Radeon ...
1
vote
3answers
5k views

Authentication very slow (both with ssh and su)

I'm having a problem on one of our production servers where the login attempts become progressively slower as time passes. After roughly 5 days it becomes so slow that some critical processes/cron ...
0
votes
0answers
36 views

Slow USB 3 write speed

Writing to my USB 3 thumb drive (SanDisk Extreme SDCZ80-064G-FFP) is very slow on Linux: 1 GB takes longer than 200s. Using Windows (dual-boot on the same computer), the same 1 GB file can be copied ...
1
vote
0answers
21 views

Why kernel may be throttled?

My MBR start freezing up for over hour and I've found that my kernel reported being throttled, e.g. (this is just a sample for 2 seconds) $ sudo fs_usage | | grep -i throttled 12:26:45 THROTTLED ...
1
vote
3answers
68 views

Is there any way of speeding up this DNS script I made? [on hold]

Part of my work is doing a lot of different DNS lookups, so I created a script that displays the information that I need in a neat fashion. Problem is it's not very fast. Doing a bash -x I can see ...
1
vote
0answers
60 views

How fast is a process reading/writing virtual memory?

We have top, htop, iotop, iostat, vmstat, etc, to measure many different things on Linux, but how can one measure how much MB/s a process is reading and writing to/from RAM, i.e., virtual memory?
1
vote
1answer
26 views

How to obtain counters for swap-in/swap-out on Linux?

I'm trying to obtain counters for swap-in/swap-out activity on CentOS 6. The intention is to feed raw data into RRDtool to generate graphs, and use it to generate alerts. I've had a look at common ...
0
votes
0answers
12 views

Performance problem Fedora 23 32-bit @ Dell D630 4GB/Nvidia

I have installed Fedora 23 32-bit at Dell D630 4GB with NVidia Quattro NVS 135M (nvidia.ko, not nouveau.ko). And I have permanent performance problem as X-Windows (Gnome) are very slow and laggy. I ...
3
votes
1answer
60 views

What is the overhead of using subshells?

Hopefully this question is not too generic. I am very new to shell scripting and I come from a computer architecture/non-scripting programming background. I have noticed on the scripts at my work that ...
2
votes
1answer
43 views

'cd' complexity on ext4

In order to store attachments, a /path/to/atts/ directory will have numerous child-directories (product IDs) created (from 1 to ~10,000 or maybe more in the future), and in each of this subdir, 1 to ...
26
votes
9answers
2k views

for vs find in Bash

When looping through files there are two ways: use a for-loop: for f in *; do echo "$f" done use find: find * -prune | while read f; do echo "$f" done Assuming these two loops will ...
1
vote
0answers
52 views

Why my server cannot serve more than 400 concurrent connections

I have an Ubuntu 14.04 LTS, kernel 3.13 in a Intel Xeon + 8Gb box. It has apache 2.4.7 configured in mpm worker with up to 4000 workers. The max bandwidth allowed by the ISP is 100Mbps. If I test ...
5
votes
4answers
3k views

Why is writing SLOW on raw device, and FAST on filesystem (USB key)?

I have a USB key (PQI U822V-Speedy 32G) that I am trying to benchmark quick'n'dirty on Linux. I'm testing write bandwith. dd on raw partition I created a partition starting at sector 2048, then did ...
8
votes
1answer
3k views

Throttling web crawlers

My website is being DoS'ed by Google webspiders. Google is welcome to index my site, but sometimes it is querying a tagcloud on my site faster than my webserver can produce the results, making my ...
1
vote
1answer
19 views

How does iotop calculate the relative I/O activity?

I am running some heavy I/O processes on my workstation and recently installed iotop to monitor them. Here's a recent screenshot: I'm a bit confused about the readings in the IO> column. It ...
3
votes
0answers
29 views

Is it bad to have thousands of autofs rules?

My company literally has thousands of NFS volumes, which we need to mount on a few of our servers. However, we never mount all of them at the same time; typically we mount about 12 at a time. Most of ...
26
votes
3answers
6k views

Is dash or some other shell “faster” than bash?

I always thought that the only benefit of using dash instead of bash was that dash was smaller, and therefore many instances of dash would start faster at boot time. But I have done some research, ...
6
votes
1answer
2k views

Audio/video out of sync when playing MP4s in mplayer

When I try to play MP4 files in mplayer, after a few seconds I get the "Your system is too SLOW to play this!" warning and the video starts lagging behind the audio. It only happens with MP4s, and ...
0
votes
0answers
10 views

Improving MPI performances on a heterogeneous cluster

I am running some parallel programs on a heterogeneous cluster: 2 CentOS virtual nodes (node 1 & node 2) on a Mac host and 2 others (node 3 & node 4) on a PC. When I run a parallel program ...
3
votes
1answer
18 views

Can I deny use of swap space to a specific process (and have it just get killed)?

While developing some software, a program under test sometimes eats all the memory, then proceeds to yomp into the swap space and start thrashing the disk, leading to a predictable drop in ...
1
vote
1answer
34 views

How to monitor system performance over time

I wrote the below script to determine how my system is holding up against various games. It checks all the vitals (GPU, RAM, and CPU) and then appends the data to a log file. Is this a reasonable ...
1
vote
1answer
19 views

What are the pros and cons of badblock's two non-destructive tests?

I use badblocks to test my 32GB class-10 microSD card that I use to boot my RPi. I already have a functioning file system on it, so I don't want to scan it with the -w option (destructive read-write ...
13
votes
1answer
184 views

Why does `find . -type f` take longer than `find .`?

It seems like find would have to check whether a given path corresponds to a file or directory anyway in order to recursively walk the contents of directories. Here's some motivation and what I've ...
2
votes
0answers
31 views

Benchmarking under SELinux Sandbox with Phoronix Test Suite

I would like to run the Phoronix Test Suite 6.2.2 under the SELinux sandbox on Fedora 23, but I can't execute it using $ sandbox ./phoronix-test-suite. I probably don't have the correct SELinux type. ...
0
votes
2answers
44 views

Can someone please explain the relation of CPU bottleneck on AIX regarding lcpu and r?

# vmstat 60 2 System configuration: lcpu=12 mem=46080MB ent=1.10 kthr memory page faults cpu ----- ----------- ------------------------ ...
2
votes
2answers
69 views

What is the best way to setup 3 HDDs with 3 OS on one computer?

I am building a new PC, I am a developer of whatever people want me to make, but I personally like to code games. To do this, I have a simple set of requirements: Machine must run Windows 7, to run ...
-3
votes
0answers
19 views

how can I address the root cause of the high “in” and “cs” at the vmstat output

root@wis-virtual-machine:~# vmstat 1 procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu----- r b swpd free buff cache si so bi bo in cs us sy id wa st ...
3
votes
1answer
58 views

How can I repeatedly send the contents of a file via socat / ncat to a socket

I'm running some performance testing, and I'm trying to send the same file repeatedly to a socket. If I do something like: $ socat -b1048576 -u OPEN:/dev/zero TCP4-LISTEN:9899,reuseaddr,fork $ ...
0
votes
1answer
903 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 ...
1
vote
1answer
40 views

Fast filesystem for virtual backup environments

I know filesystem supporters war is behind the corner and there are plenty of fine tuning guide for each filesystem in the wild, so please stick to the specifications: I'm asking what would you ...
6
votes
2answers
2k views

Massive, unpredictable I/O performance drop in Linux

I'm using Debian testing without any problems for ~6 years (I'm just regularly updating it), but recently it started to show a random behaviour that can be summarized as "Low I/O performance which ...
1
vote
1answer
75 views

UDP receive buffer error

We are running opensips SIP proxy in high traffic environment, it's using UDP protocol. We are seeing sometime RX error or overrun error on interface. I have set rmem_max to 16M but still i am seeing ...
0
votes
0answers
22 views

Ubuntu trusty format disk slower than RHEL7?

I observed that disk formatting is much slower in Ubuntu than in RHEL7. Does anybody know why that is? EDIT: Forgot to mention, I'm formatting the disk with ext4. Using mke2fs
1
vote
0answers
27 views

Configure xterm to use ctrl+shift+c/ctrl+shift+v for copy/paste?

I was using terminator for my terminal emulator, but I'm seeing huge performance issues with it. ie, launching a new terminal session takes 20-30 seconds on my netbook. gnome-terminal is better, but ...
0
votes
1answer
2k views

Physical and logical extents size

I have created a partition with 36TB (/dev/sdb1) in rhel 6.6 Now I want use this for lvm What is recommended size for Physical Extents, Volume Extents and Logical Extents How important PE, VE and LE ...
1
vote
2answers
40 views

Tracking/Monitoring Short-Lived CPU-Intensive Process on one CPU

So I've been working with this issue for some time now, and I'm having trouble finding the tools to troubleshoot this problem, which I have to imagine exist. So here's the basics of my problem: We ...
1
vote
1answer
147 views

Seq performance hit when specifying a format string

Running seq (GNU coreutils 8.21) without specifying a format string runs extremely quickly compared with any possible format I tried: $ time seq 1e8 > /dev/null seq 1e8 > /dev/null 0.68s ...
2
votes
3answers
1k views

Is cmp faster than diff -q?

In a recent Ask Ubuntu question on checking whether some files have differing content, I saw a comment stating that, if the differing sections didn't matter, cmp would be faster than diff. This Stack ...
22
votes
11answers
13k views

Lightest way to run GUI applications in Linux? [closed]

I realized I can use a window manager without a desktop environment and don't lose any functionality I care about. Applications still work fine, I can still arrange application windows as I please. ...
4
votes
2answers
179 views

Why is boot slow?

I'm using Fedora 23, MATE edition. The computer feels slow to boot. How can I speed it up? Full details http://i.imgur.com/vrLGXDp.jpg $ systemd-analyze Startup finished in 16.571s (firmware) + ...
5
votes
2answers
832 views

Why do systems become slow when doing massive writes to disk?

I want to know why systems become slow when writing mass data to disk. I think that for system to become slow, there should be some issue with CPU. But write is only I/O bound. Do hardware ...
2
votes
0answers
78 views

ZFS (on linux) performance issues

I have a server setup with RaidZ2 (8 disks in array) + 2 spares (+ system disk). The disks are 6TB each, 7200 RPM SAS The machine runs Centos7 x86_64 (not a VM), and has 128 GB of RAM and 48 cores ...
7
votes
3answers
10k views

Grep in couple thousands files

I have directory with cca 26 000 files and I need to grep in all these files. Problem is, that I need it as fast as possible, so it's not ideal to make script where grep will take name of one file ...
45
votes
2answers
4k views

Why is egrep [wW][oO][rR][dD] faster than grep -i word?

I've been using grep -i more often and I found out that it is slower than its egrep equivalent, where I match against the upper or lower case of each letter: $ time grep -iq "thats" testfile real ...
0
votes
1answer
25 views

Does RAID 0 have a performance gain even on a low resource OS like Ubuntu or Mint?

I have Windows 10 installed on raid 0 right now but I was thinking about wiping it and installing mint. I already have an i7 3770, 24gb ram and a 250gb ssd. Would there be any improvement by ...
3
votes
1answer
69 views

VAR=`cat file` and then repeating echo “$VAR” is slower than repeating cat file. Why?

There are about 10.000 files in files/ and 10.000 lines in metadata.csv. Where metadata.csv contains information about the files. I have a shell script which prints information about each file and ...
0
votes
2answers
74 views

command to list logical volume I/O statistics on AIX

I am looking for a command which displays the I/O statistics of logical volumes (like reads/sec , writes/sec, io utilization %, read kb per second, written kb per second) . I tried iostat, but its ...
4
votes
3answers
187 views

How to search efficiently for a list of strings in a big code directory

I have a list of strings, for every of those strings, I want to check if it occurs in a big source code directory. I came to a GNU grep solution that gives me what I want: for key in $(cat ...
0
votes
2answers
62 views

Memory usage and space disk on Solaris 11

How can I monitor Memory Usage: 33/512MB (6%) Disk usage: 4.2/20GB (23%) CPU Load: 0.01 on a Solaris 11 System? I want to make a script to monitor my desktop resources.
10
votes
2answers
18k views

rsync is very slow (factor 8 to 10) compared to cp on copying files from nfs-share to local dir

I have a freshly installed Ubuntu-server which is ought to be the new backup-server for our VM-storage. The server has 4 nics, 2 of them 10Gbit (in fact an intel x540-T2 with the newest driver ...