diff options
| -rw-r--r-- | block/blk-settings.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 91449147bae9..608df4674245 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -62,16 +62,24 @@ EXPORT_SYMBOL(blk_set_stacking_limits); void blk_apply_bdi_limits(struct backing_dev_info *bdi, struct queue_limits *lim) { + u64 io_opt = lim->io_opt; + /* * For read-ahead of large files to be effective, we need to read ahead - * at least twice the optimal I/O size. + * at least twice the optimal I/O size. For rotational devices that do + * not report an optimal I/O size (e.g. ATA HDDs), use the maximum I/O + * size to avoid falling back to the (rather inefficient) small default + * read-ahead size. * * There is no hardware limitation for the read-ahead size and the user * might have increased the read-ahead size through sysfs, so don't ever * decrease it. */ + if (!io_opt && (lim->features & BLK_FEAT_ROTATIONAL)) + io_opt = (u64)lim->max_sectors << SECTOR_SHIFT; + bdi->ra_pages = max3(bdi->ra_pages, - lim->io_opt * 2 / PAGE_SIZE, + io_opt * 2 >> PAGE_SHIFT, VM_READAHEAD_PAGES); bdi->io_pages = lim->max_sectors >> PAGE_SECTORS_SHIFT; } |