path: root/lib/Makefile
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authorTom Herbert <therbert@google.com>2011-11-28 16:32:35 +0000
committerDavid S. Miller <davem@davemloft.net>2011-11-29 12:46:19 -0500
commit75957ba36c05b979701e9ec64b37819adc12f830 (patch)
treec980b8489d6c09cc71ce80f61fb892e3c8806c96 /lib/Makefile
parent85c10f28286148ee5cdba1d22c81936ff160596e (diff)
dql: Dynamic queue limits
Implementation of dynamic queue limits (dql). This is a libary which allows a queue limit to be dynamically managed. The goal of dql is to set the queue limit, number of objects to the queue, to be minimized without allowing the queue to be starved. dql would be used with a queue which has these properties: 1) Objects are queued up to some limit which can be expressed as a count of objects. 2) Periodically a completion process executes which retires consumed objects. 3) Starvation occurs when limit has been reached, all queued data has actually been consumed but completion processing has not yet run, so queuing new data is blocked. 4) Minimizing the amount of queued data is desirable. A canonical example of such a queue would be a NIC HW transmit queue. The queue limit is dynamic, it will increase or decrease over time depending on the workload. The queue limit is recalculated each time completion processing is done. Increases occur when the queue is starved and can exponentially increase over successive intervals. Decreases occur when more data is being maintained in the queue than needed to prevent starvation. The number of extra objects, or "slack", is measured over successive intervals, and to avoid hysteresis the limit is only reduced by the miminum slack seen over a configurable time period. dql API provides routines to manage the queue: - dql_init is called to intialize the dql structure - dql_reset is called to reset dynamic values - dql_queued called when objects are being enqueued - dql_avail returns availability in the queue - dql_completed is called when objects have be consumed in the queue Configuration consists of: - max_limit, maximum limit - min_limit, minimum limit - slack_hold_time, time to measure instances of slack before reducing queue limit Signed-off-by: Tom Herbert <therbert@google.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib/Makefile')
1 files changed, 2 insertions, 0 deletions
diff --git a/lib/Makefile b/lib/Makefile
index a4da283f5dc..ff00d4dcb7e 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -115,6 +115,8 @@ obj-$(CONFIG_CPU_RMAP) += cpu_rmap.o
obj-$(CONFIG_CORDIC) += cordic.o
+obj-$(CONFIG_DQL) += dynamic_queue_limits.o
hostprogs-y := gen_crc32table
clean-files := crc32table.h