On 02/05/2015 11:48 AM, J. Bruce Fields wrote: > On Thu, Feb 05, 2015 at 11:43:46AM -0500, Anna Schumaker wrote: >> On 02/05/2015 11:23 AM, Christoph Hellwig wrote: >>> On Thu, Feb 05, 2015 at 11:06:04AM -0500, Anna Schumaker wrote: >>>>> If the READ_PLUS implementation can't use the splice read path it's >>>>> probably a loss for most workloads. >>>>> >>>> >>>> I'll play around with the splice path, but I don't think it was designed for encoding multiple read segments. >>> >>> The problem is that the typical case of all data won't use splice >>> every with your patches as the 4.2 client will always send a READ_PLUS. >>> >>> So we'll have to find a way to use it where it helps. While we might be >>> able to add some hacks to only use splice for the first segment I guess >>> we just need to make the splice support generic enough in the long run. >>> >> >> I should be able to use splice if I detect that we're only returning a single DATA segment easily enough. > > Oh, good thought, yes maybe that would be enough. > > But I still wish he had more evidence here. I'm not seeing a huge performance increase with READ_PLUS compared to READ (in fact, it's often a bit slower compared to READ, even when using splice). My guess is that the problem is mostly on the client's end since we have to do a memory shift on each segment to get everything lined up properly. I'm playing around with code that cuts down the number of memory shifts, but I still have a few bugs to work out before I'll know if it actually helps. Anna > > --b. > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
