On Thu, 22 Jan 2009 16:27:59 -0600 James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 2009-01-23 at 07:03 +0900, FUJITA Tomonori wrote: > > So, Boaz, what do you want to do exactly? It should have in the patch > > description. I don't want to add something that nobody uses. > > OK, can we step back a bit from this? Everyone seems to be talking past > each other. The original complaint was that multiple commands against > the same device issued by SG_IO could be executed "out of order". This > is really irrelevant because we never guarantee execution order in the > first place. > > However, if you consider our current at head insertion policy coupled > with a multi-threaded application issuing hundreds of SG_IO requests at > once, you can see we have a potential starvation issue: Commands at the > tail of the queue end up pushed further and further back as more > commands are added to the head. This starvation issue is worth > addressing, I think, and it can only be addressed by allowing tail > insertion. Ah, I see. Thanks. We could see this with something busy. BTW, bsg write interface enables you to send a command asynchronously so a single-thread-ed application could cause this. -- 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
