===================================================================
@@ -545,14 +545,28 @@ static int adjoin(struct dm_table *table
/*
* Used to dynamically allocate the arg array.
+ *
+ * We do first allocation with GFP_NOIO because dm-mpath and dm-thin must
+ * process messages even if some device is suspended. These messages have a
+ * small fixed number of arguments.
+ *
+ * On the other hand, dm-switch needs to process bulk data using messages and
+ * excessive use of GFP_NOIO could cause trouble.
*/
static char **realloc_argv(unsigned *array_size, char **old_argv)
{
char **argv;
unsigned new_size;
+ gfp_t gfp;
- new_size = *array_size ? *array_size * 2 : 64;
- argv = kmalloc(new_size * sizeof(*argv), GFP_KERNEL);
+ if (*array_size) {
+ new_size = *array_size * 2;
+ gfp = GFP_KERNEL;
+ } else {
+ new_size = 8;
+ gfp = GFP_NOIO;
+ }
+ argv = kmalloc(new_size * sizeof(*argv), gfp);
if (argv) {
memcpy(argv, old_argv, *array_size * sizeof(*argv));
*array_size = new_size;
Hi Here I'm sending the GFP_NOIO message patch. I tried the approach with double scan of the message and no reallocation, but it performs 5% worse on dm-switch table loading. So I stayed with the current approach that does single scan and argv reallocation. Mikulas --- dm: allocate buffer for messages with small number of arguments with GFP_NOIO dm-mpath and dm-thin must process messages even if some device is suspended, so we allocate argv buffer with GFP_NOIO. These messages have a small fixed number of arguments. On the other hand, dm-switch needs to process bulk data using messages and excessive use of GFP_NOIO could cause trouble. The patch also lowers the default number of arguments from 64 to 8, so that there is smaller load on GFP_NOIO allocations. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@kernel.org --- drivers/md/dm-table.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel