Sorry, please discard this patchset. We found that the previous commit: https://github.com/fujita/tgt/commit/0e23d5754d3bc3cf0328255fa7dab8547ecb6e60 improves throughput of tgtd enough. We've evaluated this patchset based on RHEL's tgt, which doesn't have the above commit. Thanks, Hitoshi On Fri, Feb 14, 2014 at 8:21 PM, Hitoshi Mitake <mitake.hitoshi@xxxxxxxxxxxxx> wrote: > Current tgtd sends and receives iSCSI PDUs in its main event > loop. This design can cause bottleneck when many iSCSI clients connect > to single tgtd process. For example, we need multiple tgtd processes > for utilizing fast network like 10 GbE because typical single > processor core isn't fast enough for processing a bunch of requests. > > This patchset lets tgtd offload send/recv iSCSI PDUs and digest checking to > worker threads. The basic strategy of this change is like below: > 1. decompose iscsi_[rt]x_handler() > 2. re-implement single threaded version of iscsi_tcp_event_handler() > 3. implement multi-threaded version of iscsi_tcp_event_handler() > > This patch also adds a new option "-T" to specify a number of threads which > send/recieve PDUs. When 1 is passed with the option, the above single threaded > version will be used, because the multi-threaded version incurs overhead which > comes from frequent communication between threads in some case. If users don't > want to use the multi-threaded version, they don't have to use it. > > Below is a summary of our performance evaluation: > - 4 physical hosts connected with 10Gbps ethernet > - 1 tgtd process provides 1 logical unit > - 16 VMs read 4GB iso file by dd command in parallel > -- average time required to complete the dd command of 16 VMs is a score > --- original tgtd: 93.718 second > --- changed tgtd (with -T 16): 57.449 second > > The above scores show that this patchset can improve performance of parallel > access of initiators. This patchset is not so heavily tested yet. I'd like to > hear your opinion about the design. > > Hitoshi Mitake (5): > tgtd: add helper functions for checking iostate of iscsi connections > tgtd: decompose iscsi_[rt]x_handler() > tgtd: add a new option "-T" for specifying a number of threads which > send/recv iSCSI PDUs > tgtd: implement a deferred event modification mechanism > tgtd: offload iSCSI PDU send/recv to worker threads > > usr/iscsi/iscsi_tcp.c | 405 +++++++++++++++++++++++++++++++++++++++++++++++-- > usr/iscsi/iscsid.c | 101 ++++++++---- > usr/iscsi/iscsid.h | 11 +- > usr/tgtd.c | 10 +- > usr/tgtd.h | 1 + > 5 files changed, 483 insertions(+), 45 deletions(-) > > -- > 1.7.10.4 > -- To unsubscribe from this list: send the line "unsubscribe stgt" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
