Jeff Garzik wrote: > Tejun Heo wrote: >> Hello, >> >> [S]ATA has lots of legacy and not in a too healthy way. The desparate >> efforts to keep everything compatible made mundane things quite >> challenging. Probing definitely is one of them. We now span from >> ancient CF devices to port multipliers and quirky ones are easy to >> find all along the spectrum. >> >> For example, according to the spec reset protocol and the actual >> implementations, there's no defined way to wait for the initial D2H >> Reg FIS after hardresetting a fan-out port. The problem is that the >> D2H Reg FIS can arrive during later steps of probing is in progress >> and a rogue FIS at the right time can easily make the controller fail >> or time out pending operations. >> >> Another problem of the long spectrum is that we can't choose the one >> correct value as timeout for operations. A timeout value which can >> cover all the devices is too long and makes EH painfully slow when >> something goes wrong. Choosing shorter timeout means the ancient and >> weirdos won't work. >> >> So, we have to resort to smart self adjusting timeouts. Early >> quickies to detect transient failures quickly and later long ones to >> cover odd devices. Deadline driven ata_eh_reset() was a step in that >> direction and this patchset, in addition to other timeout related >> improvements, applies it to the rest of EH commands. >> >> This patchset contains the following patches. >> >> 01-libata-kill-unused-constants.patch >> 02-libata-consistently-use-msecs-for-time-durations.patch >> 03-libata-improve-EH-retry-delay-handling.patch >> 04-libata-use-ULONG_MAX-to-terminate-reset-timeout-tab.patch >> 05-libata-improve-EH-internal-command-timeout-handling.patch >> >> #01, #02 and #04 are preparations. #02 makes liata use msecs >> consistently for time durations. #03 makes inter-try or inter-reset >> delays smarter and allows libata EH to delay less between tries >> without sacrificing robustness. #05 implements per command class >> stepped timeouts for EH commands, so that the first IDENTIFY try fails >> quickly but later on the device can take full 30secs to think about it >> while restricting maximum timeout for SET_FEATURES to 10secs. >> >> This patchset makes whole EH behave much more swiftly and timeout >> cases bearable. :-) > > ACK > > for .27? Seems useful to .26, but also we are late in .26-rc and this > is a lot of changes for -rc$LATE :) Yes, for .27. It's too big a change for 26. Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
