On 30.12.2014 12:07, Denis V. Lunev wrote:
On 30/12/14 13:55, Peter Lieven wrote:
Am 30.12.2014 um 10:20 schrieb Denis V. Lunev:
These patches eliminate data writes completely on Linux if fallocate
FALLOC_FL_ZERO_RANGE or FALLOC_FL_PUNCH_HOLE are supported on
underlying filesystem.
I have performed several tests with non-aligned fallocate calls and
in all cases (with non-aligned fallocates) Linux performs fine, i.e.
areas are zeroed correctly. Checks were made on
Linux 3.16.0-28-generic #38-Ubuntu SMP
This should seriously increase performance in some special cases.
Could you give a hint what that special cases are? It would help
to evaluate and test the performance difference.
Thanks,
Peter
- 15% in Parallels Image expansion, see my side patchset
I will have a look.
- writing zeroes to raw image with BLOCKDEV_DETECT_ZEROES_OPTIONS_ON set
(actually I have kludged raw-posix.c to have this flag always set
to perform independent testing)
Is there a valid reason to write chunks of >16MB blocksize from a guest? Or is
this
just users performing pseudo benchmarks with dd?
Peter
