On Sat, Apr 01, 2017 at 06:46:24PM +0200, Michael van Elst wrote: > On Sat, Apr 01, 2017 at 11:12:42AM -0400, Thor Lancelot Simon wrote: > > > That said, very high-latency transports like iSCSI require a lot more > > data than we can put into flight at once. We just don't have enough > > parallelism in our I/O subsystem (and most applications can't supply > > enough). > > We have tons of parallelism for writing and a small amount for reading.
Unless you've done even more than I noticed, allocation in the filesystems is going to be a bottleneck -- concurrent access not having been foremost in anyone's mind when FFS was designed. XFS is full of tricks for this. Unfortunately, despite a few early papers, the source code pretty much is the documentation -- and parts of the code that were effectively hamstrung by the lesser capabilities of the early Linux kernel compared to end-of-the-road Irix have in some cases been removed. -- Thor Lancelot Simon t...@panix.com "We cannot usually in social life pursue a single value or a single moral aim, untroubled by the need to compromise with others." - H.L.A. Hart