What does hdparm mean by “buffer cache”; hardware cache in hard drive or page cache in computer memory?

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
2
down vote

favorite
2












From hdparm man page:



-t Perform timings of device reads for benchmark and comparison
purposes. For meaningful results, this operation should be
repeated 2-3 times on an otherwise inactive system (no other
active processes) with at least a couple of megabytes of free
memory. This displays the speed of reading through the buffer
cache to the disk without any prior caching of data. This
measurement is an indication of how fast the drive can sustain
sequential data reads under Linux, without any filesystem
overhead. To ensure accurate measurements, the buffer cache is
flushed during the processing of -t using the BLKFLSBUF ioctl.


What is the "buffer cache"?



  • The hardware cache/buffer in hard drives and in some ssd drives?

  • The caching that the OS does using RAM, ie not using the cache on the harddrive. I think this is called page caching.

  • Both

Maybe it's obvious for most, but it is not for me :)







share|improve this question























    up vote
    2
    down vote

    favorite
    2












    From hdparm man page:



    -t Perform timings of device reads for benchmark and comparison
    purposes. For meaningful results, this operation should be
    repeated 2-3 times on an otherwise inactive system (no other
    active processes) with at least a couple of megabytes of free
    memory. This displays the speed of reading through the buffer
    cache to the disk without any prior caching of data. This
    measurement is an indication of how fast the drive can sustain
    sequential data reads under Linux, without any filesystem
    overhead. To ensure accurate measurements, the buffer cache is
    flushed during the processing of -t using the BLKFLSBUF ioctl.


    What is the "buffer cache"?



    • The hardware cache/buffer in hard drives and in some ssd drives?

    • The caching that the OS does using RAM, ie not using the cache on the harddrive. I think this is called page caching.

    • Both

    Maybe it's obvious for most, but it is not for me :)







    share|improve this question





















      up vote
      2
      down vote

      favorite
      2









      up vote
      2
      down vote

      favorite
      2






      2





      From hdparm man page:



      -t Perform timings of device reads for benchmark and comparison
      purposes. For meaningful results, this operation should be
      repeated 2-3 times on an otherwise inactive system (no other
      active processes) with at least a couple of megabytes of free
      memory. This displays the speed of reading through the buffer
      cache to the disk without any prior caching of data. This
      measurement is an indication of how fast the drive can sustain
      sequential data reads under Linux, without any filesystem
      overhead. To ensure accurate measurements, the buffer cache is
      flushed during the processing of -t using the BLKFLSBUF ioctl.


      What is the "buffer cache"?



      • The hardware cache/buffer in hard drives and in some ssd drives?

      • The caching that the OS does using RAM, ie not using the cache on the harddrive. I think this is called page caching.

      • Both

      Maybe it's obvious for most, but it is not for me :)







      share|improve this question











      From hdparm man page:



      -t Perform timings of device reads for benchmark and comparison
      purposes. For meaningful results, this operation should be
      repeated 2-3 times on an otherwise inactive system (no other
      active processes) with at least a couple of megabytes of free
      memory. This displays the speed of reading through the buffer
      cache to the disk without any prior caching of data. This
      measurement is an indication of how fast the drive can sustain
      sequential data reads under Linux, without any filesystem
      overhead. To ensure accurate measurements, the buffer cache is
      flushed during the processing of -t using the BLKFLSBUF ioctl.


      What is the "buffer cache"?



      • The hardware cache/buffer in hard drives and in some ssd drives?

      • The caching that the OS does using RAM, ie not using the cache on the harddrive. I think this is called page caching.

      • Both

      Maybe it's obvious for most, but it is not for me :)









      share|improve this question










      share|improve this question




      share|improve this question









      asked May 2 at 12:48









      Mads Skjern

      2401310




      2401310

























          active

          oldest

          votes











          Your Answer







          StackExchange.ready(function()
          var channelOptions =
          tags: "".split(" "),
          id: "106"
          ;
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function()
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled)
          StackExchange.using("snippets", function()
          createEditor();
          );

          else
          createEditor();

          );

          function createEditor()
          StackExchange.prepareEditor(
          heartbeatType: 'answer',
          convertImagesToLinks: false,
          noModals: false,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: null,
          bindNavPrevention: true,
          postfix: "",
          onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          );



          );








           

          draft saved


          draft discarded


















          StackExchange.ready(
          function ()
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f441316%2fwhat-does-hdparm-mean-by-buffer-cache-hardware-cache-in-hard-drive-or-page-ca%23new-answer', 'question_page');

          );

          Post as a guest



































          active

          oldest

          votes













          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes










           

          draft saved


          draft discarded


























           


          draft saved


          draft discarded














          StackExchange.ready(
          function ()
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2funix.stackexchange.com%2fquestions%2f441316%2fwhat-does-hdparm-mean-by-buffer-cache-hardware-cache-in-hard-drive-or-page-ca%23new-answer', 'question_page');

          );

          Post as a guest













































































          Popular posts from this blog

          How to check contact read email or not when send email to Individual?

          Displaying single band from multi-band raster using QGIS

          How many registers does an x86_64 CPU actually have?