Matthew Wilcox wrote: > On Sun, Jun 22, 2008 at 03:16:49PM +0300, Boaz Harrosh wrote: >> Matthew Wilcox wrote: >>> Use the noop elevator by default for drives that do not spin >>> >> <snip> >>> I've brazenly stolen sd_vpd_inquiry from mkp's patch here: >>> >>> http://marc.info/?l=linux-scsi&m=121264354724277&w=2 >>> >>> No need to have two copies of that ... but this will conflict with his code. >>> >> <snip> >>> I think there's an opportunity to improve sd_vpd_inquiry() to remove >>> some of the duplicate code between sd_set_elevator() and sd_block_limits, >>> but it's not terribly important. >>> >>> +static int sd_vpd_inquiry(struct scsi_disk *sdkp, unsigned char *buffer, u8 page, u8 len) >>> +{ >>> + int result; >>> + unsigned char cmd[16]; >>> + struct scsi_sense_hdr sshdr; >>> + >>> + memset(cmd, 0, 16); >>> + cmd[0] = INQUIRY; >>> + cmd[1] = 1; /* EVPD */ >>> + cmd[2] = page; /* VPD page */ >>> + cmd[3] = len; >>> + >>> + result = scsi_execute_req(sdkp->device, cmd, DMA_FROM_DEVICE, buffer, >>> + len, &sshdr, SD_TIMEOUT, SD_MAX_RETRIES); >>> + >>> + if (media_not_present(sdkp, &sshdr)) >>> + return -EIO; >>> + >>> + if (result) { >>> + sd_printk(KERN_ERR, sdkp, "EVPD Inquiry failed\n"); >>> + return -EIO; >>> + } >>> + >>> + if (buffer[1] != page) { >>> + sd_printk(KERN_ERR, sdkp, "Page code not %2x (%2x)\n", page, >>> + buffer[1]); >>> + return -EIO; >>> + } >>> + >>> + return buffer[3]; >>> +} >> I was just copy/pasting the same code into my ULD. Perhaps the low level of above >> could be made into a scsi_vpd_inquiry(...). From a quick search it looks like there >> are 3 more places that issue _vpd_inquiry in the tree today. > > Yes, there's nothing sd-specific about it. Let me just make that minor > improvement and I'll send out a proposal for scsi_vpd_inquiry(). > >> Some of the more interesting device information are in vpd's. we should have a generic >> user-mode way to inquire them. sysfs structure, ioctl, I'm not sure, something good for >> udev. There are tones of such little knobs that could be tuned according to vpd >> information. > > We have sg_inq and sg_vpd from Doug's sg3-utils. > >> Thanks for doing this, I will investigate if current iscsi-targets will immediately benefit >> from this too. From my testing I found that it is usually better to let the target side >> elevator do the work, and set the Initiator elevator to noop. Do you know what the standard >> say about the default value should be, in the case the page is not present. I would assume >> it means "No spinning media" too, right? > > It means "Not reported". Which I translate from standard-ese as > "Could be anything". > OK Thanks. I'll make sure all iscsi targets I care about return this page. Am anticipating this patchset to be submitted, thanks again. Boaz -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
