| Message ID | 20111011031145.9587.93507.sendpatchset@skannery.in.ibm.com |
|---|---|
| State | New |
| Headers | show |
Am 11.10.2011 05:11, schrieb Supriya Kannery: > qemu command option 'hostcache' added to -drive for block devices. > While starting a VM from qemu commandline, this option can be used > for setting host cache usage for block data access. Simultaneous > use of 'hostcache' and 'cache' options not allowed. > > Signed-off-by: Supriya Kannery <supriyak@linux.vnet.ibm.com> I'm not sure if introducing this alone makes sense. I think I would only do it when we introduce more options that allow replacing all cache=... options by other parameters. > > --- > blockdev.c | 13 +++++++++++++ > qemu-config.c | 4 ++++ > qemu-options.hx | 2 +- > 3 files changed, 18 insertions(+), 1 deletion(-) > > Index: qemu/blockdev.c > =================================================================== > --- qemu.orig/blockdev.c > +++ qemu/blockdev.c > @@ -237,6 +237,7 @@ DriveInfo *drive_init(QemuOpts *opts, in > DriveInfo *dinfo; > int snapshot = 0; > int ret; > + int hostcache = 0; > > translation = BIOS_ATA_TRANSLATION_AUTO; > media = MEDIA_DISK; > @@ -319,7 +320,19 @@ DriveInfo *drive_init(QemuOpts *opts, in > } > } > > + if ((hostcache = qemu_opt_get_bool(opts, "hostcache", -1)) != -1) { > + if (!hostcache) { > + bdrv_flags |= BDRV_O_NOCACHE; > + } else { > + bdrv_flags &= ~BDRV_O_NOCACHE; > + } bdrv_flags is initialised to 0, so the else branch is unnecessary. Kevin
On 10/12/2011 08:00 PM, Kevin Wolf wrote: > Am 11.10.2011 05:11, schrieb Supriya Kannery: >> qemu command option 'hostcache' added to -drive for block devices. >> While starting a VM from qemu commandline, this option can be used >> for setting host cache usage for block data access. Simultaneous >> use of 'hostcache' and 'cache' options not allowed. >> >> Signed-off-by: Supriya Kannery<supriyak@linux.vnet.ibm.com> > > I'm not sure if introducing this alone makes sense. I think I would only > do it when we introduce more options that allow replacing all cache=... > options by other parameters. > Can we do transition to alternatives for 'cache=' in a phased manner? Until all other params are ready, we can allow hostcache (as well as other params as and when they are ready) in cmdline with the condition that 'cache=x', if specified, overrides these params. Once we have all other params ready, 'cache=' can be replaced completely. thanks, Supriya
Am 14.10.2011 13:19, schrieb Supriya Kannery: > On 10/12/2011 08:00 PM, Kevin Wolf wrote: >> Am 11.10.2011 05:11, schrieb Supriya Kannery: >>> qemu command option 'hostcache' added to -drive for block devices. >>> While starting a VM from qemu commandline, this option can be used >>> for setting host cache usage for block data access. Simultaneous >>> use of 'hostcache' and 'cache' options not allowed. >>> >>> Signed-off-by: Supriya Kannery<supriyak@linux.vnet.ibm.com> >> >> I'm not sure if introducing this alone makes sense. I think I would only >> do it when we introduce more options that allow replacing all cache=... >> options by other parameters. >> > > Can we do transition to alternatives for 'cache=' in a phased manner? > Until all other params are ready, we can allow hostcache (as well > as other params as and when they are ready) in cmdline with the > condition that 'cache=x', if specified, overrides these params. > Once we have all other params ready, 'cache=' can be replaced completely. I guess that would be good enough. There's still not much use in specifying hostcache=... at the same time as cache=... but at least it doesn't take away other options then. Kevin
Index: qemu/blockdev.c =================================================================== --- qemu.orig/blockdev.c +++ qemu/blockdev.c @@ -237,6 +237,7 @@ DriveInfo *drive_init(QemuOpts *opts, in DriveInfo *dinfo; int snapshot = 0; int ret; + int hostcache = 0; translation = BIOS_ATA_TRANSLATION_AUTO; media = MEDIA_DISK; @@ -319,7 +320,19 @@ DriveInfo *drive_init(QemuOpts *opts, in } } + if ((hostcache = qemu_opt_get_bool(opts, "hostcache", -1)) != -1) { + if (!hostcache) { + bdrv_flags |= BDRV_O_NOCACHE; + } else { + bdrv_flags &= ~BDRV_O_NOCACHE; + } + } + if ((buf = qemu_opt_get(opts, "cache")) != NULL) { + if (hostcache != -1) { + error_report("'hostcache' and 'cache' cannot co-exist"); + return NULL; + } if (bdrv_parse_cache_flags(buf, &bdrv_flags) != 0) { error_report("invalid cache option"); return NULL; Index: qemu/qemu-options.hx =================================================================== --- qemu.orig/qemu-options.hx +++ qemu/qemu-options.hx @@ -135,7 +135,7 @@ DEF("drive", HAS_ARG, QEMU_OPTION_drive, " [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n" " [,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n" " [,serial=s][,addr=A][,id=name][,aio=threads|native]\n" - " [,readonly=on|off]\n" + " [,readonly=on|off][,hostcache=on|off]\n" " use 'file' as a drive image\n", QEMU_ARCH_ALL) STEXI @item -drive @var{option}[,@var{option}[,@var{option}[,...]]] Index: qemu/qemu-config.c =================================================================== --- qemu.orig/qemu-config.c +++ qemu/qemu-config.c @@ -85,6 +85,10 @@ static QemuOptsList qemu_drive_opts = { .name = "readonly", .type = QEMU_OPT_BOOL, .help = "open drive file as read-only", + },{ + .name = "hostcache", + .type = QEMU_OPT_BOOL, + .help = "set or reset hostcache (on/off)" }, { /* end of list */ } },
qemu command option 'hostcache' added to -drive for block devices. While starting a VM from qemu commandline, this option can be used for setting host cache usage for block data access. Simultaneous use of 'hostcache' and 'cache' options not allowed. Signed-off-by: Supriya Kannery <supriyak@linux.vnet.ibm.com> --- blockdev.c | 13 +++++++++++++ qemu-config.c | 4 ++++ qemu-options.hx | 2 +- 3 files changed, 18 insertions(+), 1 deletion(-)