Messages in this thread | | | From | "Nicholas A. Bellinger" <> | Subject | [RFC 0/2] target: Add TFO->complete_irq queue_work bypass | Date | Fri, 22 May 2015 07:57:24 +0000 |
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From: Nicholas Bellinger <nab@linux-iscsi.org>
Hi HCH & Co,
Here is RFC code for adding target_core_fabric_ops->complete_irq bypass that allows fabrics to invoke response callbacks directly from target_complete_cmd() IRQ context.
It breaks up existing target_complete_ok_work() code into three pieces:
- transport_complete_task_attr() - target_complete_ok_pre() - target_complete_irq()
and allows target_complete_irq() be called directly from IRQ context if no special case se_cmd handling requirements exist.
The three cases that trigger queue_work() process context are:
- non GOOD status - ORDERED task sync - non NULL se_cmd->transport_complete_callback()
It also includes converting target_restart_delayed_cmds() to use llist_head, and checking within transport_complete_task_attr() to determine if dev_ordered_sync is non zero, ahead of doing the llist_del_all() -> cmpxchg of outstanding ordered tags.
This allows loopback LLD code to bypass the extra queue_work, and invoke it's ->scsi_done() callback directly from IRQ context.
WDYT..?
--nab
Nicholas Bellinger (2): target: Add support for fabric IRQ completion loopback: Enable TFO->complete_irq for fast-path ->scsi_done
drivers/target/loopback/tcm_loop.c | 1 + drivers/target/target_core_device.c | 2 +- drivers/target/target_core_tpg.c | 1 + drivers/target/target_core_transport.c | 165 ++++++++++++++++++++++++--------- include/target/target_core_base.h | 5 +- include/target/target_core_fabric.h | 1 + 6 files changed, 127 insertions(+), 48 deletions(-)
-- 1.9.1
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