From e647f351da2c6601a3e280b5c3477421e981ca73 Mon Sep 17 00:00:00 2001 From: Stefan Haberland Date: Wed, 5 Aug 2026 13:15:58 +0200 Subject: [PATCH] s390/dasd: Optimize max blocks per request for track alignment MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Stefan Haberland Link: https://patch.msgid.link/20260805111612.1285190-6-sth@linux.ibm.com Signed-off-by: Jens Axboe --- 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 /*****************************************************************************