> 2025年7月16日 19:37，Christoph Hellwig <hch@xxxxxx> 写道： > > On Wed, Jul 16, 2025 at 02:02:41AM +0800, colyli@xxxxxxxxxx wrote: >> From: Coly Li <colyli@xxxxxxxxxx> >> >> Currently in md_submit_bio() the incoming request bio is split by >> bio_split_to_limits() which makes sure the bio won't exceed >> max_hw_sectors of a specific raid level before senting into its >> .make_request method. >> >> For raid level 4/5/6 such split method might be problematic and hurt >> large read/write perforamnce. Because limits.max_hw_sectors are not >> always aligned to limits.io_opt size, the split bio won't be full >> stripes covered on all data disks, and will introduce extra read-in I/O. >> Even the bio's bi_sector is aligned to limits.io_opt size and large >> enough, the resulted split bio is not size-friendly to corresponding >> raid456 level. > > So why don't you set a sane max_hw_sectors value instead of duplicating > the splitting logic? Can you explain a bit more detail? In case I misunderstand you like I did with Kuai’s comments. Thanks. Coly Li
