Merge branch 'tc-etf' into iproute2-next
Jesus Sanchez-Palencia says: ==================== fixes since v3: - Add support for clock names with the "CLOCK_" prefix; - Print clock name on print_opt(); - Use strcasecmp() instead of strncasecmp(). The ETF (earliest txtime first) qdisc was recently merged into net-next [1], so this patchset adds support for it through the tc command line tool. An initial man page is also provided. The first commit in this series is adding an updated version of include/uapi/linux/pkt_sched.h and is not meant to be merged. It's provided here just as a convenience for those who want to easily build this patchset. [1] https://patchwork.ozlabs.org/cover/938991/ ==================== Signed-off-by: David Ahern <dsahern@gmail.com>
This commit is contained in:
David Ahern
commit
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.TH ETF 8 "05 Jul 2018" "iproute2" "Linux"
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.SH NAME
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ETF \- Earliest TxTime First (ETF) Qdisc
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.SH SYNOPSIS
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.B tc qdisc ... dev
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dev
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.B parent
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classid
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.B [ handle
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major:
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.B ] etf clockid
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clockid
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.B [ delta
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delta_nsecs
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.B ] [ deadline_mode ]
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.B [ offload ]
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.SH DESCRIPTION
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The ETF (Earliest TxTime First) qdisc allows applications to control
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the instant when a packet should be dequeued from the traffic control
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layer into the netdevice. If
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.B offload
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is configured and supported by the network interface card, the it will
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also control when packets leave the network controller.
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ETF achieves that by buffering packets until a configurable time
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before their transmission time (i.e. txtime, or deadline), which can
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be configured through the
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.B delta
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option.
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The qdisc uses a rb-tree internally so packets are always 'ordered' by
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their txtime and will be dequeued following the (next) earliest txtime
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first.
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It relies on the SO_TXTIME socket option and the SCM_TXTIME CMSG in
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each packet field to configure the behavior of time dependent sockets:
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the clockid to be used as a reference, if the expected mode of txtime
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for that socket is deadline or strict mode, and if packet drops should
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be reported on the socket's error queue. See
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.BR socket(7)
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for more information.
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The etf qdisc will drop any packets with a txtime in the past, or if a
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packet expires while waiting for being dequeued.
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This queueing discipline is intended to be used by TSN (Time Sensitive
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Networking) applications, and it exposes a traffic shaping functionality
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that is commonly documented as "Launch Time" or "Time-Based Scheduling"
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by vendors and the documentation of network interface controllers.
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ETF is meant to be installed under another qdisc that maps packet flows
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to traffic classes, one example is
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.BR mqprio(8).
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.SH PARAMETERS
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.TP
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clockid
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.br
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Specifies the clock to be used by qdisc's internal timer for measuring
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time and scheduling events. The qdisc expects that packets passing
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through it to be using this same
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.B clockid
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as the reference of their txtime timestamps. It will drop packets
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coming from sockets that do not comply with that.
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For more information about time and clocks on Linux, please refer
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to
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.BR time(7)
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and
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.BR clock_gettime(3).
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.TP
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delta
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.br
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After enqueueing or dequeueing a packet, the qdisc will schedule its
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next wake-up time for the next txtime minus this delta value.
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This means
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.B delta
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can be used as a fudge factor for the scheduler latency of a system.
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This value must be specified in nanoseconds.
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The default value is 0 nanoseconds.
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.TP
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deadline_mode
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.br
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When
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.B deadline_mode
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is set, the qdisc will handle txtime with a different semantics,
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changed from a 'strict' transmission time to a deadline.
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In practice, this means during the dequeue flow
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.BR etf(8)
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will set the txtime of the packet being dequeued to 'now'.
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The default is for this option to be disabled.
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.TP
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offload
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.br
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When
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.B offload
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is set,
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.BR etf(8)
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will try to configure the network interface so time-based transmission
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arbitration is enabled in the controller. This feature is commonly
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referred to as "Launch Time" or "Time-Based Scheduling" by the
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documentation of network interface controllers.
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The default is for this option to be disabled.
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.SH EXAMPLES
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ETF is used to enforce a Quality of Service. It controls when each
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packets should be dequeued and transmitted, and can be used for
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limiting the data rate of a traffic class. To separate packets into
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traffic classes the user may choose
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.BR mqprio(8),
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and configure it like this:
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.EX
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# tc qdisc add dev eth0 handle 100: parent root mqprio num_tc 3 \\
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map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \\
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queues 1@0 1@1 2@2 \\
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hw 0
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.EE
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.P
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To replace the current queueing discipline by ETF in traffic class
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number 0, issue:
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.P
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.EX
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# tc qdisc replace dev eth0 parent 100:1 etf \\
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clockid CLOCK_TAI delta 300000 offload
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.EE
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With the options above, etf will be configured to use CLOCK_TAI as
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its clockid_t, will schedule packets for 300 us before their txtime,
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and will enable the functionality on that in the network interface
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card. Deadline mode will not be configured for this mode.
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.SH AUTHORS
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Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
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.br
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Vinicius Costa Gomes <vinicius.gomes@intel.com>
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@ -71,6 +71,7 @@ TCMODULES += q_clsact.o
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TCMODULES += e_bpf.o
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TCMODULES += f_matchall.o
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TCMODULES += q_cbs.o
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TCMODULES += q_etf.o
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TCSO :=
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ifeq ($(TC_CONFIG_ATM),y)
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@ -0,0 +1,181 @@
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/*
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* q_etf.c Earliest TxTime First (ETF).
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Vinicius Costa Gomes <vinicius.gomes@intel.com>
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* Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <string.h>
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#include "utils.h"
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#include "tc_util.h"
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#define CLOCKID_INVALID (-1)
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static const struct static_clockid {
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const char *name;
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clockid_t clockid;
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} clockids_sysv[] = {
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{ "REALTIME", CLOCK_REALTIME },
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{ "TAI", CLOCK_TAI },
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{ "BOOTTIME", CLOCK_BOOTTIME },
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{ "MONOTONIC", CLOCK_MONOTONIC },
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{ NULL }
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};
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static void explain(void)
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{
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fprintf(stderr, "Usage: ... etf delta NANOS clockid CLOCKID [offload] [deadline_mode]\n");
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fprintf(stderr, "CLOCKID must be a valid SYS-V id (i.e. CLOCK_TAI)\n");
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}
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static void explain1(const char *arg, const char *val)
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{
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fprintf(stderr, "etf: illegal value for \"%s\": \"%s\"\n", arg, val);
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}
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static void explain_clockid(const char *val)
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{
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fprintf(stderr, "etf: illegal value for \"clockid\": \"%s\".\n", val);
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fprintf(stderr, "It must be a valid SYS-V id (i.e. CLOCK_TAI)\n");
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}
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static int get_clockid(__s32 *val, const char *arg)
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{
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const struct static_clockid *c;
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/* Drop the CLOCK_ prefix if that is being used. */
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if (strcasestr(arg, "CLOCK_") != NULL)
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arg += sizeof("CLOCK_") - 1;
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for (c = clockids_sysv; c->name; c++) {
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if (strcasecmp(c->name, arg) == 0) {
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*val = c->clockid;
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return 0;
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}
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}
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return -1;
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}
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static const char* get_clock_name(clockid_t clockid)
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{
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const struct static_clockid *c;
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for (c = clockids_sysv; c->name; c++) {
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if (clockid == c->clockid)
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return c->name;
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}
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return "invalid";
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}
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static int etf_parse_opt(struct qdisc_util *qu, int argc,
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char **argv, struct nlmsghdr *n, const char *dev)
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{
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struct tc_etf_qopt opt = {
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.clockid = CLOCKID_INVALID,
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};
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struct rtattr *tail;
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while (argc > 0) {
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if (matches(*argv, "offload") == 0) {
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if (opt.flags & TC_ETF_OFFLOAD_ON) {
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fprintf(stderr, "etf: duplicate \"offload\" specification\n");
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return -1;
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}
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opt.flags |= TC_ETF_OFFLOAD_ON;
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} else if (matches(*argv, "deadline_mode") == 0) {
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if (opt.flags & TC_ETF_DEADLINE_MODE_ON) {
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fprintf(stderr, "etf: duplicate \"deadline_mode\" specification\n");
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return -1;
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}
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opt.flags |= TC_ETF_DEADLINE_MODE_ON;
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} else if (matches(*argv, "delta") == 0) {
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NEXT_ARG();
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if (opt.delta) {
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fprintf(stderr, "etf: duplicate \"delta\" specification\n");
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return -1;
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}
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if (get_s32(&opt.delta, *argv, 0)) {
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explain1("delta", *argv);
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return -1;
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}
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} else if (matches(*argv, "clockid") == 0) {
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NEXT_ARG();
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if (opt.clockid != CLOCKID_INVALID) {
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fprintf(stderr, "etf: duplicate \"clockid\" specification\n");
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return -1;
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}
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if (get_clockid(&opt.clockid, *argv)) {
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explain_clockid(*argv);
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return -1;
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}
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} else if (strcmp(*argv, "help") == 0) {
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explain();
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return -1;
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} else {
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fprintf(stderr, "etf: unknown parameter \"%s\"\n", *argv);
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explain();
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return -1;
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}
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argc--; argv++;
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}
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tail = NLMSG_TAIL(n);
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addattr_l(n, 1024, TCA_OPTIONS, NULL, 0);
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addattr_l(n, 2024, TCA_ETF_PARMS, &opt, sizeof(opt));
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tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
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return 0;
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}
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static int etf_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
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{
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struct rtattr *tb[TCA_ETF_MAX+1];
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struct tc_etf_qopt *qopt;
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if (opt == NULL)
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return 0;
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parse_rtattr_nested(tb, TCA_ETF_MAX, opt);
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if (tb[TCA_ETF_PARMS] == NULL)
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return -1;
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qopt = RTA_DATA(tb[TCA_ETF_PARMS]);
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if (RTA_PAYLOAD(tb[TCA_ETF_PARMS]) < sizeof(*qopt))
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return -1;
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print_string(PRINT_ANY, "clockid", "clockid %s ",
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get_clock_name(qopt->clockid));
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print_uint(PRINT_ANY, "delta", "delta %d ", qopt->delta);
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print_string(PRINT_ANY, "offload", "offload %s ",
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(qopt->flags & TC_ETF_OFFLOAD_ON) ? "on" : "off");
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print_string(PRINT_ANY, "deadline_mode", "deadline_mode %s",
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(qopt->flags & TC_ETF_DEADLINE_MODE_ON) ? "on" : "off");
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return 0;
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}
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struct qdisc_util etf_qdisc_util = {
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.id = "etf",
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.parse_qopt = etf_parse_opt,
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.print_qopt = etf_print_opt,
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};
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