On Fri, Feb 13 2015 at 8:27P -0500,
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:
> Write requests are sorted in a red-black tree structure and are submitted
> in the sorted order.
>
> In theory the sorting should be performed by the underlying disk scheduler,
> however, in practice the disk scheduler accepts and sorts only 128 requests.
> In order to sort more requests, we need to implement our own sorting.
>
> In testing, it was shown that this patch slightly increases performance in
> some situations
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
FYI, I've folded this patch in to cleanup rb_tree node access:
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 954ba1f..e6a1460 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1175,9 +1175,13 @@ static void kcryptd_io_write(struct dm_crypt_io *io)
generic_make_request(clone);
}
+#define crypt_io_from_node(node) rb_entry((node), struct dm_crypt_io, rb_node)
+
static int dmcrypt_write(void *data)
{
struct crypt_config *cc = data;
+ struct dm_crypt_io *io;
+
while (1) {
struct rb_root write_tree;
struct blk_plug plug;
@@ -1221,8 +1225,7 @@ pop_from_list:
*/
blk_start_plug(&plug);
do {
- struct dm_crypt_io *io = rb_entry(rb_first(&write_tree),
- struct dm_crypt_io, rb_node);
+ io = crypt_io_from_node(rb_first(&write_tree));
rb_erase(&io->rb_node, &write_tree);
kcryptd_io_write(io);
} while (!RB_EMPTY_ROOT(&write_tree));
@@ -1237,7 +1240,7 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async)
struct crypt_config *cc = io->cc;
unsigned long flags;
sector_t sector;
- struct rb_node **p, *parent;
+ struct rb_node **rbp, *parent;
if (unlikely(io->error < 0)) {
crypt_free_buffer_pages(cc, clone);
@@ -1252,19 +1255,17 @@ static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async)
clone->bi_iter.bi_sector = cc->start + io->sector;
spin_lock_irqsave(&cc->write_thread_wait.lock, flags);
- p = &cc->write_tree.rb_node;
+ rbp = &cc->write_tree.rb_node;
parent = NULL;
sector = io->sector;
- while (*p) {
- parent = *p;
-#define io_node rb_entry(parent, struct dm_crypt_io, rb_node)
- if (sector < io_node->sector)
- p = &io_node->rb_node.rb_left;
+ while (*rbp) {
+ parent = *rbp;
+ if (sector < crypt_io_from_node(parent)->sector)
+ rbp = &(*rbp)->rb_left;
else
- p = &io_node->rb_node.rb_right;
-#undef io_node
+ rbp = &(*rbp)->rb_right;
}
- rb_link_node(&io->rb_node, parent, p);
+ rb_link_node(&io->rb_node, parent, rbp);
rb_insert_color(&io->rb_node, &cc->write_tree);
wake_up_locked(&cc->write_thread_wait);
--
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