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To fix the issue(system freeze when copy large file) i changed the scheduler from cfq to deadline. I am not sure that scheduler affect the swap uses or not. I have 8 GB of ram, 2.0 GHz corei7 processor and 8 GB swap. swappiness value is low but Ubuntu still using 10 MB swap space and system stuck when try to switch the windows. I have attached a screenshot of gnome-system-monitor. I was downloading 4-5 large files( >=1.5 GB <= 4.0 GB) and watching a 720p movie using gnome-mplayer.

cat /sys/block/sda/queue/scheduler
noop [deadline] cfq 

cat /proc/sys/vm/swappiness
10

sudo hdparm -I /dev/sda
ATA device, with non-removable media
    Model Number:       WDC WD10JPVX-80JC3T0                    
    Serial Number:      WD-WX11AA3E8770
    Firmware Revision:  01.01A01
    Transport:          Serial, SATA 1.0a, SATA II Extensions, SATA Rev 2.5, SATA Rev 2.6, SATA Rev 3.0
Standards:
    Supported: 9 8 7 6 5 
    Likely used: 9
Configuration:
    Logical     max current
    cylinders   16383   16383
    heads       16  16
    sectors/track   63  63

enter image description here

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  • 3
    I wouldn't call 10MB "lots".
    – muru
    Dec 12, 2014 at 15:09
  • @muru vm.swappiness=10, so it's lot in sense that I have 63% ram available.
    – shantanu
    Dec 12, 2014 at 15:10
  • Nope. A small duration of high memory usage may cause a process to be swapped out, and if it's not awakened soon enough, it may not be swapped back in, 10 MB is fair. You have only shown us ~20s worth of RAM usage. What about an hour or more?
    – muru
    Dec 12, 2014 at 15:14
  • 2
    You have 8 GiB of swap space total. 10 MiB is a tenth of a percent of that. Definitely not "lots." If you only had 10 MiB of swap, then it would certainly be "lots." You don't state anything about what type of disk you are using though. It sounds to me more like your issue is that copying large files is causing heavy disk I/O, which is causing delays in processing.
    – dobey
    Dec 12, 2014 at 15:19
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    @edwardtorvalds I fight the same problem often, and I believe it to be a page cache issue rather than a swap issue: if I cause the cache to be flushed, my system becomes responsive again. Dec 12, 2014 at 17:30

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