----- Original Message ----- From: Benjamin Kaduk <[email protected]> To: [email protected] Cc: [email protected] Date: Tue, 20 Mar 2012 23:42:44 -0400 (EDT) Subject: Re: BUG: REL 9.0 - MD malloc of custom sector size
> On Tue, 20 Mar 2012, [email protected] wrote: > > > ----- Original Message ----- > > From: RW <[email protected]> > > To: [email protected] > > Date: Sun, 18 Mar 2012 13:41:56 +0000 > > Subject: Re: BUG: REL 9.0 - MD malloc of custom sector size > > > >> On Sun, 18 Mar 2012 14:01:39 +0100 > >> [email protected] wrote: > >> > >>> man mdconfig > >>> ---- > >>> -S sectorsize to use for malloc backed device > >>> ---- > >>> > >>> I want to create MD device, with sector size of 4 Kb. > >>> > >>> It is CRITICAL to NOT append ANY suffixes, when specifing size, via > >>> '-s' flag in order to use sectors, to set it's size. # mdconfig -a -t > >>> malloc -S 4096 -s 32768 > >>> > >>> This should created dev of 128 Mb in size. > >>> 32768 sectors * 4 Kb each = 131072 Kb = 128 Mb > >>> Not! It created dev of 16 Mb in size, because sector size remained at > >>> 512 bytes. > >> > >> > >> From mdconfig 8 > >> > >> "Size is the number of 512 byte sectors unless ..." > >> > >> Looks to me like it's doing what it said it would. > >> > >> BTW are you sure you want to use "-t malloc". This keeps the files > >> (even the deleted ones) in memory unconditionally while ordinary > >> process memory is paged-out. > >> > > > > My MAIN reason to hassle with MD here, is to test a custom sector size. > > This can be done with '-S' flag only, in order to set sectorsize of /dev/md* > > But as it is malloc ONLY option/flag, I must combine it with '-t malloc' > > > > Then I've defined it's size by amount of sectors and as I've redefined > > size of 1 sector, it simply isn't doing it's task. Because it enforces > > hardcoded size of 512 bytes, so documentation should not misleadingly > > refer to sector in any way, but a hardcode value of 0.5 Kb, no matter of > > real/actual sector size is. > > It should not be technically challenging to cause mdconfig to have the -s > size argument in terms of -S sectorsize sized sectors; the following would > probably suffice (untested): > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > Index: mdconfig.c > =================================================================== > --- mdconfig.c (revision 233159) > +++ mdconfig.c (working copy) > @@ -94,16 +94,19 @@ > int > main(int argc, char **argv) > { > - int ch, fd, i, vflag; > + int ch, fd, i, vflag, sflag; > char *p; > char *fflag = NULL, *tflag = NULL, *uflag = NULL; > + unsigned bsize; > > bzero(&mdio, sizeof(mdio)); > mdio.md_file = malloc(PATH_MAX); > if (mdio.md_file == NULL) > err(1, "could not allocate memory"); > vflag = 0; > + sflag = 0; > bzero(mdio.md_file, PATH_MAX); > + bsize = DEV_BSIZE; > > if (argc == 1) > usage(); > @@ -186,11 +189,12 @@ > break; > case 'S': > mdio.md_sectorsize = strtoul(optarg, &p, 0); > + bsize = mdio.md_sectorsize; > break; > case 's': > mdio.md_mediasize = (off_t)strtoumax(optarg, &p, 0); > if (p == NULL || *p == '\0') > - mdio.md_mediasize *= DEV_BSIZE; > + sflag = 1; > else if (*p == 'b' || *p == 'B') > ; /* do nothing */ > else if (*p == 'k' || *p == 'K') > @@ -232,6 +236,9 @@ > if (action == UNSET) > action = ATTACH; > > + if (sflag == 1) > + mdio.md_mediasize *= bsize; > + > if (action == ATTACH) { > if (tflag == NULL) { > /* > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > > Or would you prefer a man page change? I would prefer both. Above patch to make it default to sector size of 512 bytes, IF not overridden with -S flag (then sector size is set to it) Instead to a hardcoded value of 512 bytes. And manpages to document that ... (just mention sectorsize - it's size may vary) > > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > Index: mdconfig.8 > =================================================================== > --- mdconfig.8 (revision 233159) > +++ mdconfig.8 (working copy) > @@ -132,7 +132,7 @@ > .It Fl s Ar size > Size of the memory disk. > .Ar Size > -is the number of 512 byte sectors unless suffixed with a > +is measured in increments of 512 byes unless suffixed with a > .Cm b , k , m , g , > or > .Cm t > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > > BTW I do not see where -S is a malloc-only option; please show the command > line and error message using a vnode- or swap-backed device. > > -Ben Kaduk > From man pages: ---- -S sectorsize Sectorsize to use for MALLOC backed device. ---- When I tried: # mdconfig -S 4096 -nf /usr/IT usage: mdconfig -a -t type [-n] [-o [no]option] ... [-f file] [-s size] [-S sectorsize] [-u unit] [-x sectors/track] [-y heads/cylinder] ... ---- So it made me into thinking that manpages were correct. However, when I've tried this, it worked: ------------ # mdconfig -nf /usr/IT -S 4096 # diskinfo -v md0 md0 4096 # sectorsize 2147483648 # mediasize in bytes (2.0G) 524288 # mediasize in sectors 0 # stripesize 0 # stripeoffset ------------ Man page for -S flag, should be updated, to note that only INT value (without SI suffixes) is accepted, which represents bytes. This didn't work: -S 4k Actually it did! I've ended up with device of 4 byte sector size! :P Domagoj Smolčić _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[email protected]"
