On Tue, Dec 31, 2019 at 12:19 AM Bart Van Assche <bvanassche@xxxxxxx> wrote: > > On 2019-12-30 02:29, Jack Wang wrote: > > diff --git a/drivers/infiniband/ulp/rtrs/README b/drivers/infiniband/ulp/rtrs/README > > Other kernel driver documentation exists under the Documentation/ > directory. Should this README file perhaps be moved to a subdirectory of > the Documentation/ directory? I did check most of the drivers are in the drivers directory eg: find ./ -name README ./fs/reiserfs/README ./fs/qnx4/README ./fs/qnx6/README ./fs/cramfs/README ./Documentation/ABI/README ./Documentation/virt/kvm/devices/README ./README ./tools/usb/usbip/README ./tools/virtio/ringtest/README ./tools/virtio/virtio-trace/README ./tools/power/pm-graph/README ./tools/power/cpupower/README ./tools/memory-model/README ./tools/memory-model/scripts/README ./tools/memory-model/litmus-tests/README ./tools/testing/vsock/README ./tools/testing/ktest/examples/README ./tools/testing/selftests/ftrace/README ./tools/testing/selftests/arm64/signal/README ./tools/testing/selftests/arm64/README ./tools/testing/selftests/android/ion/README ./tools/testing/selftests/zram/README ./tools/testing/selftests/livepatch/README ./tools/testing/selftests/net/forwarding/README ./tools/testing/selftests/futex/README ./tools/testing/selftests/tc-testing/README ./tools/thermal/tmon/README ./tools/build/tests/ex/empty2/README ./tools/perf/tests/attr/README ./tools/perf/pmu-events/README ./tools/perf/scripts/perl/Perf-Trace-Util/README ./tools/io_uring/README ./net/decnet/README ./scripts/ksymoops/README ./scripts/selinux/README ./arch/powerpc/boot/README ./arch/m68k/q40/README ./arch/m68k/ifpsp060/README ./arch/m68k/fpsp040/README ./arch/parisc/math-emu/README ./arch/x86/math-emu/README ./drivers/bcma/README ./drivers/char/mwave/README ./drivers/staging/nvec/README ./drivers/staging/wlan-ng/README ./drivers/staging/axis-fifo/README ./drivers/staging/fbtft/README ./drivers/staging/fsl-dpaa2/ethsw/README ./drivers/staging/goldfish/README ./drivers/staging/gs_fpgaboot/README ./drivers/staging/comedi/drivers/ni_routing/README ./drivers/net/wireless/marvell/mwifiex/README ./drivers/net/wireless/marvell/libertas/README > > > +**************************** > > +InfiniBand Transport (RTRS) > > +**************************** > > The abbreviation does not match the full title. Do you agree that this > is confusing? > > > +RTRS is used by the RNBD (Infiniband Network Block Device) modules. > > Is RNBD an RDMA or an InfiniBand network block device? will fix. > > > + > > +================== > > +Transport protocol > > +================== > > + > > +Overview > > +-------- > > +An established connection between a client and a server is called rtrs > > +session. A session is associated with a set of memory chunks reserved on the > > +server side for a given client for rdma transfer. A session > > +consists of multiple paths, each representing a separate physical link > > +between client and server. Those are used for load balancing and failover. > > +Each path consists of as many connections (QPs) as there are cpus on > > +the client. > > + > > +When processing an incoming rdma write or read request rtrs client uses memory > > A quote from > https://linuxplumbersconf.org/event/4/contributions/367/attachments/331/555/LPC_2019_RMDA_MC_IBNBD_IBTRS_Upstreaming.pdf: > "Only RDMA writes with immediate". Has the wire protocol perhaps been > changed such that both RDMA reads and writes are used? I haven't found > any references to RDMA reads in the "IO path" section in this file. Did > I perhaps overlook something? > > Thanks, > > Bart. We do not use RDMA_READ, only RDMA_WRITE/RDMA_WRITE_WITH_IMM/SEND_WITH_IMM SEND_WITH_IMM was used only when always_invalidate=Y. Will extend the document. Thanks Bart.
