On Wed, 24 Jun 2009 21:01:08 +0100 Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > On Wed, Jun 10, 2009 at 01:51:25PM -0700, H. Peter Anvin wrote: > > Andrew Morton wrote: > > > > > > hm, OK. > > > > > > I've now mounted 15000 devpts's and still no slowdown is evident. > > > > I ran my test script, mounting ramfs, with n=100000, and well, gave up > > since it hadn't gotten any further than 57000 or so overnight. At that > > time each individual mount was taking several seconds. > > > > Graphing the delays seem to indicate O(n^2) behavior. > > > > umounts do not appear affected; each umount still take negible time. > > I think I know what's going on. /sbin/mount is linked against libselinux > /sbin/umount is not. And FPOS in question blows if you > * do not have selinuxfs mounted (e.g. because selinux is not enabled) > * have a lot of mounts. > > What happens is that this piece of crap checks for presence of selinuxfs > on /selinux; then, if the thing isn't there, we go and scan the entire > /proc/mounts in search of selinuxfs mounts. > > If akpm has selinux enabled on his testbox and you don't have it on yours, > we have all observations explained. CONFIG_SECURITY_SELINUX=y CONFIG_SECURITY_SELINUX_BOOTPARAM=y CONFIG_SECURITY_SELINUX_BOOTPARAM_VALUE=1 CONFIG_SECURITY_SELINUX_DISABLE=y CONFIG_SECURITY_SELINUX_DEVELOP=y CONFIG_SECURITY_SELINUX_AVC_STATS=y CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE=1 # CONFIG_SECURITY_SELINUX_ENABLE_SECMARK_DEFAULT is not set # CONFIG_SECURITY_SELINUX_POLICYDB_VERSION_MAX is not set > I'd expect similar slowdown from > ls on an empty directory, BTW - /bin/ls is linked against the same thing, > so it gets hit as well. Before it even gets to main(). -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
