Hi XFS list,
please find attached a patch for libdisk/mkfs.xfs which tunes XFS on
software partitionable RAID arrays, also called mdp.
Hubert Verstraete
Hubert Verstraete wrote:
Bill Davidsen wrote:
Luca Berra wrote:
On Tue, Mar 25, 2008 at 05:57:06PM +0100, Hubert Verstraete wrote:
Neil Brown wrote:
On Thursday March 13, hubskml@xxxxxxx wrote:
Neil,
What is the status of the major for the partitionable arrays ?
automatically determined at runtime.
I see that it is 254, which is in the experimental section,
according to the official Linux device list
(http://www.lanana.org/docs/device-list/).
Will there be an official registration ?
No. Is there any need?
I got this question in mind when I saw that mkfs.xfs source code was
referring to the MD major to tune its parameters on an MD device,
while it ignores MDP devices.
If there were reasons to register MD, wouldn't they apply to MDP too ?
i don't think so:
bluca@percy ~ $ grep mdp /proc/devices
253 mdp
Why is it important to have XFS tune its parameters for md and not for
mdp? I don't understand your conclusion here, is tuning not needed for
mdp, or so meaningless that it doesn't matter, or that XFS code reads
/proc/devices, or ??? I note that device-mapper also has a dynamic
major, what does XFS make of that?
It reads from /proc/devices.
I don't know how much difference tuning makes, but if it's worth doing
at all, it should be done for mdp as well, I would think.
Same thought. I wrote the patch for mkfs.xfs but did not publish it for
two reasons:
1) MD is registered but not MDP. Now I understand, it's not a problem,
we just need to read /proc/devices as device-mapper does.
2) Tuning XFS for MDP can be achieved through the mkfs.xfs options. With
a few lines in shell, my XFS on MDP now has the same performance as XFS
on MD.
Hubert
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
diff -u -r xfsprogs-2.8.11/libdisk/md.c xfsprogs-2.8.11-mdp/libdisk/md.c
--- xfsprogs-2.8.11/libdisk/md.c 2006-06-26 07:01:15.000000000 +0200
+++ xfsprogs-2.8.11-mdp/libdisk/md.c 2008-03-26 20:12:38.000000000 +0100
@@ -24,8 +24,12 @@
dev_t dev)
{
if (major(dev) == MD_MAJOR)
- return 1;
- return get_driver_block_major("md", major(dev));
+ return MD_IS_MD;
+ if (get_driver_block_major("md", major(dev)))
+ return MD_IS_MD;
+ if (get_driver_block_major("mdp", major(dev)))
+ return MD_IS_MDP;
+ return 0;
}
int
@@ -37,12 +41,32 @@
int *sectalign,
struct stat64 *sb)
{
- if (mnt_is_md_subvol(sb->st_rdev)) {
+ char *pc, *dfile2 = NULL;
+ int is_md;
+
+ if ((is_md = mnt_is_md_subvol(sb->st_rdev))) {
struct md_array_info md;
int fd;
+ if (is_md == MD_IS_MDP) {
+ if (!(pc = strrchr(dfile, 'd'))
+ || !(pc = strchr(pc, 'p'))) {
+ fprintf(stderr,
+ _("Error getting MD array device from %s\n"),
+ dfile);
+ exit(1);
+ }
+ dfile2 = (char *) malloc(pc - dfile + 1);
+ if (dfile2 == NULL) {
+ fprintf(stderr,
+ _("Couldn't malloc device string\n"));
+ exit(1);
+ }
+ strncpy(dfile2, dfile, pc - dfile);
+ dfile2[pc - dfile + 1] = '\0';
+ }
/* Open device */
- fd = open(dfile, O_RDONLY);
+ fd = open(dfile2 ? dfile2 : dfile, O_RDONLY);
if (fd == -1)
return 0;
@@ -50,10 +74,11 @@
if (ioctl(fd, GET_ARRAY_INFO, &md)) {
fprintf(stderr,
_("Error getting MD array info from %s\n"),
- dfile);
+ dfile2 ? dfile2 : dfile);
exit(1);
}
close(fd);
+ if (dfile2) free(dfile2);
/*
* Ignore levels we don't want aligned (e.g. linear)
diff -u -r xfsprogs-2.8.11/libdisk/md.h xfsprogs-2.8.11-mdp/libdisk/md.h
--- xfsprogs-2.8.11/libdisk/md.h 2006-06-26 07:01:15.000000000 +0200
+++ xfsprogs-2.8.11-mdp/libdisk/md.h 2008-03-26 20:12:10.000000000 +0100
@@ -20,6 +20,9 @@
#define MD_MAJOR 9 /* we also check at runtime */
#endif
+#define MD_IS_MD 1
+#define MD_IS_MDP 2
+
#define GET_ARRAY_INFO _IOR (MD_MAJOR, 0x11, struct md_array_info)
#define MD_SB_CLEAN 0
