[PATCH 05/19] s390/dasd: Optimize max blocks per request for track alignment

From
Stefan Haberland <sth@linux.ibm.com>
Date
2026-08-05 11:16:27
Also in
linux-s390
Reply to
Stefan Haberland, 2026-08-05
With 4096-byte blocks a full ECKD track holds exactly 12 records. Lower
DASD_ECKD_MAX_BLOCKS from 190 to 180 so requests align to track
boundaries (15 full tracks); full-track I/O is more efficient than
partial-track writes, and 190 had no alignment significance and could
let a request cross a track boundary.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
---
 drivers/s390/block/dasd_eckd.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/s390/block/dasd_eckd.h b/drivers/s390/block/dasd_eckd.h
index f9299bd184ba..763733bcc4d2 100644
--- a/drivers/s390/block/dasd_eckd.h
+++ b/drivers/s390/block/dasd_eckd.h
@@ -131,7 +131,7 @@
 /*
  * Maximum number of blocks to be chained
  */
-#define DASD_ECKD_MAX_BLOCKS		 190
+#define DASD_ECKD_MAX_BLOCKS		 180
 #define DASD_ECKD_MAX_BLOCKS_RAW	 256
 
 /*****************************************************************************
-- 
2.53.0
Thread (21 messages) 21 messages, 2 authors, last reply 2026-08-05
Keyboard shortcuts
hback out one level
jnext message in thread / next series-diff position
kprevious message in thread / previous series-diff position
ldrill in
Escclose help / fold thread tree
?toggle this help