Re: [libvirt] [PATCH v2 0/2] Add support for zero-write detection

On 12/14/2015 09:57 AM, Martin Kletzander wrote: > QEMU supports detect-zeroes option since version 2.1, but we never > added support for it in libvirt. If was requested by Vasiliy Tolstov > in the list, so I just added it. > > There are two discussions to be had, optionally. One is to decide > whether we should disable detect_zeros='unmap' if discard is not set > to 'unmap', but this is getting very hypervisor-specific, so I just > documented the behaviour. The other one is the naming. I described > why I made the decision for "zeros" instead of "zeroes" the decision > in the patch, but I have no problem changing it to what others like > better. Unfortunate that qemu chose "zeroes" instead of "zeros" or instead of "detect_zero_writes" (or something even longer and more descriptive). Seems strange though to say "detect_zeros=unmap". Would perhaps something like : detect = zero_write [or just zero, zeros, or zeroes] detect = unmap ... or detect_zero = write detect_zero = unmap ... Be more generic? Also, I would think detect_zero[e]s = off is meaningless since it's an optional parameter. The way the code is written, passing detect_zeroes=off to me would be akin to not providing it at all.

I think from my quick read - this would be similar to the "discard" option, w.r.t. values used/set. John > > v2: > - format detect_zeroes on the command line instead of detect_zeros > > v1: > - https://www.redhat.com/archives/libvir-list/2015-December/msg00484.html > > Martin Kletzander (2): > conf: Add support of zero-detection for disks > qemu: Add support for zero-detection writes > > docs/formatdomain.html.in | 10 ++++++ > docs/schemas/domaincommon.rng | 12 +++++++ > src/conf/domain_conf.c | 23 +++++++++++++- > src/conf/domain_conf.h | 11 +++++++ > src/libvirt_private.syms | 2 ++ > src/qemu/qemu_capabilities.c | 2 ++ > src/qemu/qemu_capabilities.h | 1 + > src/qemu/qemu_command.c | 11 +++++++ > tests/qemucapabilitiesdata/caps_2.1.1-1.caps | 1 + > tests/qemucapabilitiesdata/caps_2.4.0-1.caps | 1 + > tests/qemucapabilitiesdata/caps_2.5.0-1.caps | 1 + > .../qemuxml2argv-disk-drive-detect-zeros.args | 27 ++++++++++++++++ > .../qemuxml2argv-disk-drive-detect-zeros.xml | 37 ++++++++++++++++++++++ > tests/qemuxml2argvtest.c | 4 +++ > tests/qemuxml2xmltest.c | 1 + > 15 files changed, 143 insertions(+), 1 deletion(-) > create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-detect-zeros.args > create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-disk-drive-detect-zeros.xml > > -- > 2.6.4 > > -- > libvir-list mailing list > libvir-list(a)redhat.com > https://www.redhat.com/mailman/listinfo/libvir-list >