On 07.05.2014 17:19, Kevin Wolf wrote:
Am 07.05.2014 um 16:26 hat Peter Lieven geschrieben:
On 07.05.2014 04:52, Eric Blake wrote:
On 05/06/2014 06:23 PM, Peter Lieven wrote:
this patch tries to optimize zero write requests
by automatically using bdrv_write_zeroes if it is
supported by the format.
This significantly speeds up file system initialization and
should speed zero write test used to test backend storage
performance.
Signed-off-by: Peter Lieven <address@hidden>
---
v2->v3: - moved parameter parsing to blockdev_init
- added per device detect_zeroes status to
hmp (info block -v) and qmp (query-block) [Eric]
- added support to enable detect-zeroes also
for hot added devices [Eric]
- added missing entry to qemu_common_drive_opts
- fixed description of qemu_iovec_is_zero [Fam]
+static BdrvDetectZeroes parse_detect_zeroes(const char *buf, Error **errp)
+{
+ if (!buf || !strcmp(buf, "off")) {
+ return BDRV_DETECT_ZEROES_OFF;
+ } else if (!strcmp(buf, "on")) {
+ return BDRV_DETECT_ZEROES_ON;
+ } else if (!strcmp(buf, "unmap")) {
+ return BDRV_DETECT_ZEROES_UNMAP;
+ } else {
+ error_setg(errp, "invalid value for detect-zeroes: %s",
+ buf);
+ }
+ return BDRV_DETECT_ZEROES_OFF;
+}
Isn't there QAPI generated code that you can use instead of open-coding
this conversion between string and enum values?
Actually I have no idea. As you pointed out in the qapi patch I sent
it was quite hard for me to crawl through the whole stuff as one who is not
familiar with it. Can somebody advise here? Anyhow, I wonder
how this would work since qapi doesn't know the C Macros.
QAPI does generate C enums, so you should take whatever identifier it
uses instead of defining your own macros. You may need to include
qapi-types.h for this. It also creates a *_lookup array that maps enum
IDs to strings.
Ah, cool stuff, thank you. I found the enum and the lookup array,
but is there also a function that maps a string to an enum ID?