Add ''-C'' (nocow) option to vhd-util create.
Btrfs has terrible performance when hosting VM images, even more when the guest
in those VM are also using btrfs as file system. One way to mitigate this bad
performance is to turn off COW attributes on VM files (since having copy on
write for this kind of data is not useful). According to
''chattr'' manpage, NOCOW
could be set to new or empty file only on btrfs, so add a option here so that
users could have a chance to set NOCOW to a vhd image.
Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
tools/blktap2/include/libvhd.h | 1 +
tools/blktap2/vhd/lib/libvhd.c | 24 ++++++++++++++++++++++++
tools/blktap2/vhd/lib/vhd-util-create.c | 8 ++++++--
3 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/tools/blktap2/include/libvhd.h b/tools/blktap2/include/libvhd.h
index 8e854e4..fd0ca75 100644
--- a/tools/blktap2/include/libvhd.h
+++ b/tools/blktap2/include/libvhd.h
@@ -87,6 +87,7 @@
#define VHD_OPEN_IGNORE_DISABLED 0x00010
#define VHD_FLAG_CREAT_PARENT_RAW 0x00001
+#define VHD_FLAG_CREAT_NOCOW 0x00002
#define vhd_flag_set(word, flag) ((word) |= (flag))
#define vhd_flag_clear(word, flag) ((word) &= ~(flag))
diff --git a/tools/blktap2/vhd/lib/libvhd.c b/tools/blktap2/vhd/lib/libvhd.c
index 95eb5d6..12a9667 100644
--- a/tools/blktap2/vhd/lib/libvhd.c
+++ b/tools/blktap2/vhd/lib/libvhd.c
@@ -41,6 +41,14 @@
#include "libvhd.h"
#include "relative-path.h"
+#ifdef __linux__
+#include <linux/fs.h>
+#include <sys/ioctl.h>
+#ifndef FS_NOCOW_FL
+#define FS_NOCOW_FL 0x00800000 /* Do not cow file */
+#endif
+#endif
+
/* VHD uses an epoch of 12:00AM, Jan 1, 2000. This is the Unix timestamp for
* the start of the VHD epoch. */
#define VHD_EPOCH_START 946684800
@@ -2829,6 +2837,7 @@ __vhd_create(const char *name, const char *parent,
uint64_t bytes, int type,
vhd_footer_t *footer;
vhd_header_t *header;
uint64_t size, blks;
+ int attr;
switch (type) {
case HD_TYPE_DIFF:
@@ -2855,6 +2864,21 @@ __vhd_create(const char *name, const char *parent,
uint64_t bytes, int type,
if (ctx.fd == -1)
return -errno;
+ if (flags & VHD_FLAG_CREAT_NOCOW) {
+ flags &= ~VHD_FLAG_CREAT_NOCOW;
+#ifdef __linux__
+ /* Set NOCOW flag to solve performance issue on fs like btrfs.
+ * This is an optimisation. The FS_IOC_SETFLAGS ioctl return value
will
+ * be ignored since any failure of this operation should not block
the
+ * left work.
+ */
+ if (ioctl(ctx.fd, FS_IOC_GETFLAGS, &attr) == 0) {
+ attr |= FS_NOCOW_FL;
+ ioctl(ctx.fd, FS_IOC_SETFLAGS, &attr);
+ }
+#endif
+ }
+
ctx.file = strdup(name);
if (!ctx.file) {
err = -ENOMEM;
diff --git a/tools/blktap2/vhd/lib/vhd-util-create.c
b/tools/blktap2/vhd/lib/vhd-util-create.c
index a9bdf05..be632f8 100644
--- a/tools/blktap2/vhd/lib/vhd-util-create.c
+++ b/tools/blktap2/vhd/lib/vhd-util-create.c
@@ -49,7 +49,7 @@ vhd_util_create(int argc, char **argv)
goto usage;
optind = 0;
- while ((c = getopt(argc, argv, "n:s:rh")) != -1) {
+ while ((c = getopt(argc, argv, "n:s:rCh")) != -1) {
switch (c) {
case ''n'':
name = optarg;
@@ -61,6 +61,10 @@ vhd_util_create(int argc, char **argv)
case ''r'':
sparse = 0;
break;
+ case ''C'':
+ /* NOCOW: this will remove COW for file on btrfs */
+ flags |= VHD_FLAG_CREAT_NOCOW;
+ break;
case ''h'':
default:
goto usage;
@@ -75,6 +79,6 @@ vhd_util_create(int argc, char **argv)
flags);
usage:
- printf("options: <-n name> <-s size (MB)> [-r reserve] [-h
help]\n");
+ printf("options: <-n name> <-s size (MB)> [-r reserve] [-C
nocow] [-h help]\n");
return -EINVAL;
}
--
1.6.0.2
Add ''-C'' (nocow) option to vhd-util create.
Btrfs has terrible performance when hosting VM images, even more when the guest
in those VM are also using btrfs as file system. One way to mitigate this bad
performance is to turn off COW attributes on VM files (since having copy on
write for this kind of data is not useful). According to
''chattr'' manpage, NOCOW
could be set to new or empty file only on btrfs, so add a option here so that
users could have a chance to set NOCOW to a vhd image.
Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
tools/blktap2/include/libvhd.h | 1 +
tools/blktap2/vhd/lib/libvhd.c | 24 ++++++++++++++++++++++++
tools/blktap2/vhd/lib/vhd-util-create.c | 8 ++++++--
3 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/tools/blktap2/include/libvhd.h b/tools/blktap2/include/libvhd.h
index 8e854e4..fd0ca75 100644
--- a/tools/blktap2/include/libvhd.h
+++ b/tools/blktap2/include/libvhd.h
@@ -87,6 +87,7 @@
#define VHD_OPEN_IGNORE_DISABLED 0x00010
#define VHD_FLAG_CREAT_PARENT_RAW 0x00001
+#define VHD_FLAG_CREAT_NOCOW 0x00002
#define vhd_flag_set(word, flag) ((word) |= (flag))
#define vhd_flag_clear(word, flag) ((word) &= ~(flag))
diff --git a/tools/blktap2/vhd/lib/libvhd.c b/tools/blktap2/vhd/lib/libvhd.c
index 95eb5d6..12a9667 100644
--- a/tools/blktap2/vhd/lib/libvhd.c
+++ b/tools/blktap2/vhd/lib/libvhd.c
@@ -41,6 +41,14 @@
#include "libvhd.h"
#include "relative-path.h"
+#ifdef __linux__
+#include <linux/fs.h>
+#include <sys/ioctl.h>
+#ifndef FS_NOCOW_FL
+#define FS_NOCOW_FL 0x00800000 /* Do not cow file */
+#endif
+#endif
+
/* VHD uses an epoch of 12:00AM, Jan 1, 2000. This is the Unix timestamp for
* the start of the VHD epoch. */
#define VHD_EPOCH_START 946684800
@@ -2829,6 +2837,7 @@ __vhd_create(const char *name, const char *parent,
uint64_t bytes, int type,
vhd_footer_t *footer;
vhd_header_t *header;
uint64_t size, blks;
+ int attr;
switch (type) {
case HD_TYPE_DIFF:
@@ -2855,6 +2864,21 @@ __vhd_create(const char *name, const char *parent,
uint64_t bytes, int type,
if (ctx.fd == -1)
return -errno;
+ if (flags & VHD_FLAG_CREAT_NOCOW) {
+ flags &= ~VHD_FLAG_CREAT_NOCOW;
+#ifdef __linux__
+ /* Set NOCOW flag to solve performance issue on fs like btrfs.
+ * This is an optimisation. The FS_IOC_SETFLAGS ioctl return value
will
+ * be ignored since any failure of this operation should not block
the
+ * left work.
+ */
+ if (ioctl(ctx.fd, FS_IOC_GETFLAGS, &attr) == 0) {
+ attr |= FS_NOCOW_FL;
+ ioctl(ctx.fd, FS_IOC_SETFLAGS, &attr);
+ }
+#endif
+ }
+
ctx.file = strdup(name);
if (!ctx.file) {
err = -ENOMEM;
diff --git a/tools/blktap2/vhd/lib/vhd-util-create.c
b/tools/blktap2/vhd/lib/vhd-util-create.c
index a9bdf05..be632f8 100644
--- a/tools/blktap2/vhd/lib/vhd-util-create.c
+++ b/tools/blktap2/vhd/lib/vhd-util-create.c
@@ -49,7 +49,7 @@ vhd_util_create(int argc, char **argv)
goto usage;
optind = 0;
- while ((c = getopt(argc, argv, "n:s:rh")) != -1) {
+ while ((c = getopt(argc, argv, "n:s:rCh")) != -1) {
switch (c) {
case ''n'':
name = optarg;
@@ -61,6 +61,10 @@ vhd_util_create(int argc, char **argv)
case ''r'':
sparse = 0;
break;
+ case ''C'':
+ /* NOCOW: this will remove COW for file on btrfs */
+ flags |= VHD_FLAG_CREAT_NOCOW;
+ break;
case ''h'':
default:
goto usage;
@@ -75,6 +79,6 @@ vhd_util_create(int argc, char **argv)
flags);
usage:
- printf("options: <-n name> <-s size (MB)> [-r reserve] [-h
help]\n");
+ printf("options: <-n name> <-s size (MB)> [-r reserve] [-C
nocow] [-h help]\n");
return -EINVAL;
}
--
1.6.0.2
On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote:> Add ''-C'' (nocow) option to vhd-util create. > > Btrfs has terrible performance when hosting VM images, even more when the guest > in those VM are also using btrfs as file system. One way to mitigate this bad > performance is to turn off COW attributes on VM files (since having copy on > write for this kind of data is not useful). According to ''chattr'' manpage, NOCOW > could be set to new or empty file only on btrfs, so add a option here so that > users could have a chance to set NOCOW to a vhd image.Is there not some btrfs (or generic) utility which could be used to do this after image creation rather than trying to build it in to every utility which creates an image file? Ian.
Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow
option"):> On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote:
> > Add ''-C'' (nocow) option to vhd-util create.
> >
> > Btrfs has terrible performance when hosting VM images, even more when
the guest
> > in those VM are also using btrfs as file system. One way to mitigate
this bad
> > performance is to turn off COW attributes on VM files (since having
copy on
> > write for this kind of data is not useful). According to
''chattr'' manpage, NOCOW
> > could be set to new or empty file only on btrfs, so add a option here
so that
> > users could have a chance to set NOCOW to a vhd image.
>
> Is there not some btrfs (or generic) utility which could be used to do
> this after image creation rather than trying to build it in to every
> utility which creates an image file?
This may seem like a daft question, but why do we even have a vhd
utility in our tree ? Is there not some vhd tools package that this
should be in ?
Ian.
On Thu, 2013-11-21 at 14:41 +0000, Ian Jackson wrote:> Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow option"): > > On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote: > > > Add ''-C'' (nocow) option to vhd-util create. > > > > > > Btrfs has terrible performance when hosting VM images, even more when the guest > > > in those VM are also using btrfs as file system. One way to mitigate this bad > > > performance is to turn off COW attributes on VM files (since having copy on > > > write for this kind of data is not useful). According to ''chattr'' manpage, NOCOW > > > could be set to new or empty file only on btrfs, so add a option here so that > > > users could have a chance to set NOCOW to a vhd image. > > > > Is there not some btrfs (or generic) utility which could be used to do > > this after image creation rather than trying to build it in to every > > utility which creates an image file? > > This may seem like a daft question, but why do we even have a vhd > utility in our tree ? Is there not some vhd tools package that this > should be in ?vhd was originally a microsoft thing and I think most OSS projects adopted it in an ad-hoc and independent manner. Most virt solutions have their own tools (e.g. qemu-img and virtualbox''s thing) for these things. I agree that it seems silly though I''m not proposing to start a separate project ;-) Ian.
Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow
option"):> On Thu, 2013-11-21 at 14:41 +0000, Ian Jackson wrote:
> > This may seem like a daft question, but why do we even have a vhd
> > utility in our tree ? Is there not some vhd tools package that this
> > should be in ?
>
> vhd was originally a microsoft thing and I think most OSS projects
> adopted it in an ad-hoc and independent manner.
>
> Most virt solutions have their own tools (e.g. qemu-img and
virtualbox''s
> thing) for these things.
>
> I agree that it seems silly though I''m not proposing to start a
separate
> project ;-)
On that basis we should probably take this patch...
Ian.
On Thu, 2013-11-21 at 14:59 +0000, Ian Jackson wrote:> Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow option"): > > On Thu, 2013-11-21 at 14:41 +0000, Ian Jackson wrote: > > > This may seem like a daft question, but why do we even have a vhd > > > utility in our tree ? Is there not some vhd tools package that this > > > should be in ? > > > > vhd was originally a microsoft thing and I think most OSS projects > > adopted it in an ad-hoc and independent manner. > > > > Most virt solutions have their own tools (e.g. qemu-img and virtualbox''s > > thing) for these things. > > > > I agree that it seems silly though I''m not proposing to start a separate > > project ;-) > > On that basis we should probably take this patch...I''m not sure it follows that because we have vhd-utils in tree we should also start incorporating btrfs-utils. Ian.
Ian Jackson wrote:> Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add -C|nocow option"): > >> On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote: >> >>> Add ''-C'' (nocow) option to vhd-util create. >>> >>> Btrfs has terrible performance when hosting VM images, even more when the guest >>> in those VM are also using btrfs as file system. One way to mitigate this bad >>> performance is to turn off COW attributes on VM files (since having copy on >>> write for this kind of data is not useful). According to ''chattr'' manpage, NOCOW >>> could be set to new or empty file only on btrfs, so add a option here so that >>> users could have a chance to set NOCOW to a vhd image. >>> >> Is there not some btrfs (or generic) utility which could be used to do >> this after image creation rather than trying to build it in to every >> utility which creates an image file? >> > > This may seem like a daft question, but why do we even have a vhd > utility in our tree ? Is there not some vhd tools package that this > should be in ? >Newer qemu-img supports vhd and vhdx right? Is there even a need for this tool at all anymore? Regards, Jim
2013/11/22 Jim Fehlig <jfehlig@suse.com>> Ian Jackson wrote: > > Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: add > -C|nocow option"): > > > >> On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote: > >> > >>> Add ''-C'' (nocow) option to vhd-util create. > >>> > >>> Btrfs has terrible performance when hosting VM images, even more when > the guest > >>> in those VM are also using btrfs as file system. One way to mitigate > this bad > >>> performance is to turn off COW attributes on VM files (since having > copy on > >>> write for this kind of data is not useful). According to ''chattr'' > manpage, NOCOW > >>> could be set to new or empty file only on btrfs, so add a option here > so that > >>> users could have a chance to set NOCOW to a vhd image. > >>> > >> Is there not some btrfs (or generic) utility which could be used to do > >> this after image creation rather than trying to build it in to every > >> utility which creates an image file? > >> > > > > This may seem like a daft question, but why do we even have a vhd > > utility in our tree ? Is there not some vhd tools package that this > > should be in ? > > > > Newer qemu-img supports vhd and vhdx right? Is there even a need for > this tool at all anymore? > >''qemu-img create'' doesn''t support creating vhd/vhdx format images. Only open/probe supported.> Regards, > Jim >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
Chunyan Liu wrote:> > > > 2013/11/22 Jim Fehlig <jfehlig@suse.com <mailto:jfehlig@suse.com>> > > Ian Jackson wrote: > > Ian Campbell writes ("Re: [Xen-devel] [PATCH] vhd-util create: > add -C|nocow option"): > > > >> On Thu, 2013-11-21 at 15:46 +0800, Chunyan Liu wrote: > >> > >>> Add ''-C'' (nocow) option to vhd-util create. > >>> > >>> Btrfs has terrible performance when hosting VM images, even > more when the guest > >>> in those VM are also using btrfs as file system. One way to > mitigate this bad > >>> performance is to turn off COW attributes on VM files (since > having copy on > >>> write for this kind of data is not useful). According to > ''chattr'' manpage, NOCOW > >>> could be set to new or empty file only on btrfs, so add a > option here so that > >>> users could have a chance to set NOCOW to a vhd image. > >>> > >> Is there not some btrfs (or generic) utility which could be > used to do > >> this after image creation rather than trying to build it in to > every > >> utility which creates an image file? > >> > > > > This may seem like a daft question, but why do we even have a vhd > > utility in our tree ? Is there not some vhd tools package that this > > should be in ? > > > > Newer qemu-img supports vhd and vhdx right? Is there even a need for > this tool at all anymore? > > > ''qemu-img create'' doesn''t support creating vhd/vhdx format images. > Only open/probe supported.Ah, I didn''t know that. Is it possible to merge vhd-util with qemu-img? You could then support nocow with something like ''qemu-img create -f vhd -o nocow, ...''. But I tend to agree with Ian that supporting backing store-specific features should be higher in the stack. E.g. a libvirt filesystem storage pool of type btrfs could support such features when creating volumes from the pool. Regards, Jim
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