On Mon, Mar 22, 2004 at 02:41:45PM -0800, Dave Olien wrote:
> While this is a big improvement, 15 second still seems a long time
> for adding that 200th PV. Likewise 29 seconds to activate the VG
> is much better. But can these be made faster?
Yes, I've a list of performance enhancements waiting to be made - they
aren't top priority yet though.
> Can these user-level commands be made smarter in this regard?
Yes.
(a) Additional internal state can be written to the cache file.
[The index of which PVs are in which VGs; the index of which
UUIDs were found on which devices.]
(b) Some disk reads are still duplicated and can be cached safely.
> Is this something that using the lvm(8) shell would help?
Yes, this is equivalent to point (a).
Either pipe the commands through it, or try linking against
the library I checked into CVS today.
(configure --enable-cmdlib; brief docn in lvm2cmd.h)
Quick example prog below.
Alasdair
#include "lvm2cmd.h"
/* All output gets passed to this function line-by-line */
void test_log_fn(int level, const char *file, int line, const char *format)
{
/* Extract and process output here instead of printing it */
if (level != 4)
return;
printf("%s\n", format);
return;
}
int main(int argc, char **argv)
{
void *handle;
int r;
lvm2_log_fn(test_log_fn);
handle = lvm2_init();
lvm2_log_level(handle, 1);
r = lvm2_run(handle, "vgs --noheadings vg1");
/* More commands here */
lvm2_exit(handle);
return r;
}
_______________________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
