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Petersen" , linux-scsi@vger.kernel.org, Bernhard Sulzer Subject: Re: [PATCH 08/14] scsi: sd: Optimal I/O size should be a multiple of reported granularity From: "Martin K. 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Petersen wrote: >> + if (min_xfer_bytes && opt_xfer_bytes & (min_xfer_bytes - 1)) { >> + sd_first_printk(KERN_WARNING, sdkp, >> + "Optimal transfer size %u bytes not a " \ >> + "multiple of preferred minimum block " \ >> + "size (%u bytes)\n", >> + opt_xfer_bytes, min_xfer_bytes); >> + return false; >> + } > > Hmm ... what guarantees that min_xfer_bytes is a power of two? Did I > perhaps overlook something? Nothing in the spec, obviously, but I think we'd have a lot of headaches further up the stack if that wasn't the case. Do you know of any devices that report something unusual here? -- Martin K. Petersen Oracle Linux Engineering