Michael Reed wrote:
In thinking about this over night, I would like to withdraw my previous comments. (Hence the snip!) Let's take the case of real time capture from a device and post processing of that data. The capture operation would likely want a fast fail to avoid dropping data. The post processing of that data would like to wait for the device to return to avoid disruption and potential premature termination of the job. Under the above scenario, assuming it's a valid scenario, are there mechanisms in place to allow an application to tag an i/o stream for fast fail?
Two comments: - This conflicts with Christoph's last comment about fast_fail failing all i/o's. I prefer the fail all, as its the easier, more straight-forward approach. Easiest to explain behavior for too. - As for tagging i/o from an application, the only places I see in the kernel setting the flags that make REQ_FAILFAST get set are strictly in-the-kernel items (multipath). I don't see any way for an application to mark this. It implies that to do what you stated above, requires the app has to serially perform each mode - and to do so at a target level. E.g. set fast fail, perform capture, set no fast fail, perform post processing. -- james s - : 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
