LU-13799 lov: Improve DIO submit

Skip some unnecessary looping in page submission for the
DIO case.

This gives about a 2% improvement for AIO/DIO page
submission.

This patch reduces i/o time in ms/GiB by:
Write: 2 ms/GiB
Read: 2 ms/GiB

Totals:
Write: 172 ms/GiB
Read: 165 ms/GiB

mpirun -np 1  $IOR -w -r -t 64M -b 64G -o ./iorfile --posix.odirect

With previous patches in series:
write        7726 MiB/s
read         5899 MiB/s

Plus this patch:
write        5954 MiB/s
read         6217 MiB/s

Signed-off-by: Patrick Farrell <farr0186@gmail.com>
Change-Id: Iedad978438ee3f1f3290d990311532626cba9e2d
Reviewed-on: https://review.whamcloud.com/39446
Reviewed-by: Wang Shilong <wshilong@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/lov/lov_io.c b/lustre/lov/lov_io.c
index 9ffd102..ae0964b 100644 (file)
--- a/lustre/lov/lov_io.c
+++ b/lustre/lov/lov_io.c
@@ -1284,12 +1284,16 @@ static int lov_io_submit(const struct lu_env *env,
        struct lov_io           *lio = cl2lov_io(env, ios);
        struct lov_io_sub       *sub;
        struct cl_page_list     *plist = &lov_env_info(env)->lti_plist;
-       struct cl_page          *page;
+       struct cl_page          *page = cl_page_list_first(qin);
        struct cl_page          *tmp;
+       bool dio = false;
        int index;
        int rc = 0;
        ENTRY;
 
+       if (page->cp_type == CPT_TRANSIENT)
+               dio = true;
+
        cl_page_list_init(plist);
        while (qin->pl_nr > 0) {
                struct cl_2queue  *cl2q = &lov_env_info(env)->lti_cl2q;
@@ -1312,12 +1316,17 @@ static int lov_io_submit(const struct lu_env *env,
                cl_page_list_move(&cl2q->c2_qin, qin, page);
 
                index = page->cp_lov_index;
-               cl_page_list_for_each_safe(page, tmp, qin) {
-                       /* this page is not on this stripe */
-                       if (index != page->cp_lov_index)
-                               continue;
-
-                       cl_page_list_move(&cl2q->c2_qin, qin, page);
+               /* DIO is already split by stripe */
+               if (!dio) {
+                       cl_page_list_for_each_safe(page, tmp, qin) {
+                               /* this page is not on this stripe */
+                               if (index != page->cp_lov_index)
+                                       continue;
+
+                               cl_page_list_move(&cl2q->c2_qin, qin, page);
+                       }
+               } else {
+                       cl_page_list_splice(qin, &cl2q->c2_qin);
                }
 
                sub = lov_sub_get(env, lio, index);