Feature #553

Add cache option to disk definition.

Added by Grzegorz Kocur over 9 years ago. Updated over 9 years ago.

Status:ClosedStart date:03/31/2011
Priority:NormalDue date:
Assignee:Ruben S. Montero% Done:

0%

Category:-
Target version:Release 3.0
Resolution:fixed Pull request:

Description

In some circumstances performance is very imported.
Unfortunately, virtual block device performance is not impressing, especially when working with qcow2 images.

It can be improved using "cache='writeback'" option.
So, please add cache parameter do block device definition.

It could be something like:

DISK = [IMAGE="image", CACHE='writeback']

Associated revisions

Revision 17edfb56
Added by Ruben S. Montero over 9 years ago

feature #553: Added cache attribute for DISK in the KVM driver

Revision fa727a7e
Added by Mariano Guezuraga almost 3 years ago

Oned: Fix typo in help (#553)

Revision 3b5a77ec
Added by Mariano Guezuraga almost 3 years ago

Oned: Fix typo in help (#553)

(cherry picked from commit fa727a7e13549d83743be4332c3a221761c62556)

History

#1 Updated by jordan pittier over 9 years ago

Here's the patch :

Edit src/vmm/LibVirtDriverKVM.cc, add around line 56

string  cache                = "";
string  default_driver_cache = "";

Edit src/vmm/LibVirtDriverKVM.cc, add around line 274

get_default("DISK","CACHE",default_driver_cache);

if (default_driver_cache.empty())
{
   default_driver_cache = "default";
}

Edit src/vmm/LibVirtDriverKVM.cc, add around line 295

cache = disk->vector_value("CACHE");

Edit the same file, starting from line 372 (considering the new line added above). The file should look like

        // ---- Image Format using qemu driver ----

        file << "\t\t\t<driver name='qemu' type='";

        if ( !driver.empty() )
        {
            file << driver << "'";
        }
        else
        {
            file << default_driver << "'";
        }

        file << " cache='";
        if ( !cache.empty() )
        {
            file << cache << "'/>" << endl;
        }
        else
        {
            file << default_driver_cache << "'/>" << endl;
        }

        file << "\t\t</disk>" << endl;

Finaly edit one/etc/vmm_ssh/vmm_ssh_kvm.conf and add something like :

DISK     = [ driver = "raw", cache = "writeback" ]

#2 Updated by Ruben S. Montero over 9 years ago

  • Assignee set to Ruben S. Montero
  • Target version set to Release 3.0

Hi,

The patch seems ok. Thanks for this :) I've schedule this feature for the next release

Ruben

#3 Updated by Ruben S. Montero over 9 years ago

  • Status changed from New to Closed
  • Resolution set to fixed

Changes in master as described here. Documentation also updated

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