• Alexander Duyck's avatar
    mm: provide kernel parameter to allow disabling page init poisoning · f682a97a
    Alexander Duyck authored
    Patch series "Address issues slowing persistent memory initialization", v5.
    The main thing this patch set achieves is that it allows us to initialize
    each node worth of persistent memory independently.  As a result we reduce
    page init time by about 2 minutes because instead of taking 30 to 40
    seconds per node and going through each node one at a time, we process all
    4 nodes in parallel in the case of a 12TB persistent memory setup spread
    evenly over 4 nodes.
    This patch (of 3):
    On systems with a large amount of memory it can take a significant amount
    of time to initialize all of the page structs with the PAGE_POISON_PATTERN
    value.  I have seen it take over 2 minutes to initialize a system with
    over 12TB of RAM.
    In order to work around the issue I had to disable CONFIG_DEBUG_VM and
    then the boot time returned to something much more reasonable as the
    arch_add_memory call completed in milliseconds versus seconds.  However in
    doing that I had to disable all of the other VM debugging on the system.
    In order to work around a kernel that might have CONFIG_DEBUG_VM enabled
    on a system that has a large amount of memory I have added a new kernel
    parameter named "vm_debug" that can be set to "-" in order to disable it.
    Link: http://lkml.kernel.org/r/20180925201921.3576.84239.stgit@localhost.localdomainReviewed-by: default avatarPavel Tatashin <pavel.tatashin@microsoft.com>
    Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@linux.intel.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Michal Hocko <mhocko@suse.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
debug.c 5.5 KB