Set the IDE DMA start bit as a separate I/O write from the DMA port

[dragonfly/vkernel-mp.git] / sys / kern / kern_poll.c

/*-
 * Copyright (c) 2001-2002 Luigi Rizzo
 *
 * Supported by: the Xorp Project (www.xorp.org)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/kern/kern_poll.c,v 1.2.2.4 2002/06/27 23:26:33 luigi Exp $
 * $DragonFly: src/sys/kern/kern_poll.c,v 1.27 2007/05/23 08:57:04 dillon Exp $
 */

#include "opt_polling.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/socket.h>                 /* needed by net/if.h           */
#include <sys/sysctl.h>

#include <sys/thread2.h>
#include <sys/msgport2.h>

#include <net/if.h>                     /* for IFF_* flags              */
#include <net/netisr.h>                 /* for NETISR_POLL              */

/* the two netisr handlers */
static int sysctl_pollhz(SYSCTL_HANDLER_ARGS);
static int sysctl_polling(SYSCTL_HANDLER_ARGS);
static void netisr_poll(struct netmsg *);
static void netisr_pollmore(struct netmsg *);
static void pollclock(systimer_t, struct intrframe *);

void init_device_poll(void);            /* init routine                 */

/*
 * Polling support for [network] device drivers.
 *
 * Drivers which support this feature try to register with the
 * polling code.
 *
 * If registration is successful, the driver must disable interrupts,
 * and further I/O is performed through the handler, which is invoked
 * (at least once per clock tick) with 3 arguments: the "arg" passed at
 * register time (a struct ifnet pointer), a command, and a "count" limit.
 *
 * The command can be one of the following:
 *  POLL_ONLY: quick move of "count" packets from input/output queues.
 *  POLL_AND_CHECK_STATUS: as above, plus check status registers or do
 *      other more expensive operations. This command is issued periodically
 *      but less frequently than POLL_ONLY.
 *  POLL_DEREGISTER: deregister and return to interrupt mode.
 *  POLL_REGISTER: register and disable interrupts
 *
 * The first two commands are only issued if the interface is marked as
 * 'IFF_UP and IFF_RUNNING', the last one only if IFF_RUNNING is set.
 *
 * The count limit specifies how much work the handler can do during the
 * call -- typically this is the number of packets to be received, or
 * transmitted, etc. (drivers are free to interpret this number, as long
 * as the max time spent in the function grows roughly linearly with the
 * count).
 *
 * Deregistration can be requested by the driver itself (typically in the
 * *_stop() routine), or by the polling code, by invoking the handler.
 *
 * Polling can be globally enabled or disabled with the sysctl variable
 * kern.polling.enable (default is 0, disabled)
 *
 * A second variable controls the sharing of CPU between polling/kernel
 * network processing, and other activities (typically userlevel tasks):
 * kern.polling.user_frac (between 0 and 100, default 50) sets the share
 * of CPU allocated to user tasks. CPU is allocated proportionally to the
 * shares, by dynamically adjusting the "count" (poll_burst).
 *
 * Other parameters can should be left to their default values.
 * The following constraints hold
 *
 *      1 <= poll_each_burst <= poll_burst <= poll_burst_max
 *      MIN_POLL_BURST_MAX <= poll_burst_max <= MAX_POLL_BURST_MAX
 */

#define MIN_POLL_BURST_MAX      10
#define MAX_POLL_BURST_MAX      1000

#ifndef DEVICE_POLLING_FREQ_MAX
#define DEVICE_POLLING_FREQ_MAX         30000
#endif
#define DEVICE_POLLING_FREQ_DEFAULT     2000

SYSCTL_NODE(_kern, OID_AUTO, polling, CTLFLAG_RW, 0,
        "Device polling parameters");

static u_int32_t poll_burst = 5;
SYSCTL_UINT(_kern_polling, OID_AUTO, burst, CTLFLAG_RW,
        &poll_burst, 0, "Current polling burst size");

static u_int32_t poll_each_burst = 5;
SYSCTL_UINT(_kern_polling, OID_AUTO, each_burst, CTLFLAG_RW,
        &poll_each_burst, 0, "Max size of each burst");

static u_int32_t poll_burst_max = 150;  /* good for 100Mbit net and HZ=1000 */
SYSCTL_UINT(_kern_polling, OID_AUTO, burst_max, CTLFLAG_RW,
        &poll_burst_max, 0, "Max Polling burst size");

static u_int32_t user_frac = 50;
SYSCTL_UINT(_kern_polling, OID_AUTO, user_frac, CTLFLAG_RW,
        &user_frac, 0, "Desired user fraction of cpu time");

static u_int32_t reg_frac = 20 ;
SYSCTL_UINT(_kern_polling, OID_AUTO, reg_frac, CTLFLAG_RW,
        &reg_frac, 0, "Every this many cycles poll register");

static u_int32_t short_ticks;
SYSCTL_UINT(_kern_polling, OID_AUTO, short_ticks, CTLFLAG_RW,
        &short_ticks, 0, "Hardclock ticks shorter than they should be");

static u_int32_t lost_polls;
SYSCTL_UINT(_kern_polling, OID_AUTO, lost_polls, CTLFLAG_RW,
        &lost_polls, 0, "How many times we would have lost a poll tick");

static u_int32_t pending_polls;
SYSCTL_UINT(_kern_polling, OID_AUTO, pending_polls, CTLFLAG_RW,
        &pending_polls, 0, "Do we need to poll again");

static int residual_burst = 0;
SYSCTL_INT(_kern_polling, OID_AUTO, residual_burst, CTLFLAG_RW,
        &residual_burst, 0, "# of residual cycles in burst");

static u_int32_t poll_handlers; /* next free entry in pr[]. */
SYSCTL_UINT(_kern_polling, OID_AUTO, handlers, CTLFLAG_RD,
        &poll_handlers, 0, "Number of registered poll handlers");

static int polling_enabled = 0;         /* global polling enable */
TUNABLE_INT("kern.polling.enable", &polling_enabled);
SYSCTL_PROC(_kern_polling, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
        0, 0, sysctl_polling, "I", "Polling enabled");

static u_int32_t phase;
SYSCTL_UINT(_kern_polling, OID_AUTO, phase, CTLFLAG_RW,
        &phase, 0, "Polling phase");

static u_int32_t suspect;
SYSCTL_UINT(_kern_polling, OID_AUTO, suspect, CTLFLAG_RW,
        &suspect, 0, "suspect event");

static u_int32_t stalled;
SYSCTL_UINT(_kern_polling, OID_AUTO, stalled, CTLFLAG_RW,
        &stalled, 0, "potential stalls");

static int pollhz = DEVICE_POLLING_FREQ_DEFAULT;
TUNABLE_INT("kern.polling.pollhz", &pollhz);
SYSCTL_PROC(_kern_polling, OID_AUTO, pollhz, CTLTYPE_INT | CTLFLAG_RW,
            0, 0, sysctl_pollhz, "I", "Device polling frequency");

#define POLL_LIST_LEN  128
struct pollrec {
        struct ifnet    *ifp;
};

static struct pollrec pr[POLL_LIST_LEN];
static struct systimer gd0_pollclock;

/*
 * register relevant netisr. Called from kern_clock.c:
 */
void
init_device_poll(void)
{
        netisr_register(NETISR_POLL, cpu0_portfn, netisr_poll);
        netisr_register(NETISR_POLLMORE, cpu0_portfn, netisr_pollmore);
        systimer_init_periodic_nq(&gd0_pollclock, pollclock, NULL, 
                                  polling_enabled ? pollhz : 1);
}

/*
 * Set the polling frequency
 */
static int
sysctl_pollhz(SYSCTL_HANDLER_ARGS)
{
        int error, phz;

        phz = pollhz;
        error = sysctl_handle_int(oidp, &phz, 0, req);
        if (error || req->newptr == NULL)
                return error;
        if (phz <= 0)
                return EINVAL;
        else if (phz > DEVICE_POLLING_FREQ_MAX)
                phz = DEVICE_POLLING_FREQ_MAX;

        crit_enter();
        pollhz = phz;
        if (polling_enabled)
                systimer_adjust_periodic(&gd0_pollclock, phz);
        crit_exit();
        return 0;
}

/*
 * Master enable.  If polling is disabled, cut the polling systimer 
 * frequency to 1hz.
 */
static int
sysctl_polling(SYSCTL_HANDLER_ARGS)
{
        int error, enabled;

        enabled = polling_enabled;
        error = sysctl_handle_int(oidp, &enabled, 0, req);
        if (error || req->newptr == NULL)
                return error;
        polling_enabled = enabled;
        if (polling_enabled)
                systimer_adjust_periodic(&gd0_pollclock, pollhz);
        else
                systimer_adjust_periodic(&gd0_pollclock, 1);
        return 0;
}

/*
 * Hook from hardclock. Tries to schedule a netisr, but keeps track
 * of lost ticks due to the previous handler taking too long.
 * Normally, this should not happen, because polling handler should
 * run for a short time. However, in some cases (e.g. when there are
 * changes in link status etc.) the drivers take a very long time
 * (even in the order of milliseconds) to reset and reconfigure the
 * device, causing apparent lost polls.
 *
 * The first part of the code is just for debugging purposes, and tries
 * to count how often hardclock ticks are shorter than they should,
 * meaning either stray interrupts or delayed events.
 *
 * WARNING! called from fastint or IPI, the MP lock might not be held.
 */
static void
pollclock(systimer_t info __unused, struct intrframe *frame __unused)
{
        static struct timeval prev_t, t;
        int delta;

        if (poll_handlers == 0)
                return;

        microuptime(&t);
        delta = (t.tv_usec - prev_t.tv_usec) +
                (t.tv_sec - prev_t.tv_sec)*1000000;
        if (delta * hz < 500000)
                short_ticks++;
        else
                prev_t = t;

        if (pending_polls > 100) {
                /*
                 * Too much, assume it has stalled (not always true
                 * see comment above).
                 */
                stalled++;
                pending_polls = 0;
                phase = 0;
        }

        if (phase <= 2) {
                if (phase != 0)
                        suspect++;
                phase = 1;
                schednetisr(NETISR_POLL);
                phase = 2;
        }
        if (pending_polls++ > 0)
                lost_polls++;
}

/*
 * netisr_pollmore is called after other netisr's, possibly scheduling
 * another NETISR_POLL call, or adapting the burst size for the next cycle.
 *
 * It is very bad to fetch large bursts of packets from a single card at once,
 * because the burst could take a long time to be completely processed, or
 * could saturate the intermediate queue (ipintrq or similar) leading to
 * losses or unfairness. To reduce the problem, and also to account better for
 * time spent in network-related processing, we split the burst in smaller
 * chunks of fixed size, giving control to the other netisr's between chunks.
 * This helps in improving the fairness, reducing livelock (because we
 * emulate more closely the "process to completion" that we have with
 * fastforwarding) and accounting for the work performed in low level
 * handling and forwarding.
 */

static struct timeval poll_start_t;

/* ARGSUSED */
static void
netisr_pollmore(struct netmsg *msg)
{
        struct timeval t;
        int kern_load;

        crit_enter();
        lwkt_replymsg(&msg->nm_lmsg, 0);
        phase = 5;
        if (residual_burst > 0) {
                schednetisr(NETISR_POLL);
                /* will run immediately on return, followed by netisrs */
                goto out;
        }
        /* here we can account time spent in netisr's in this tick */
        microuptime(&t);
        kern_load = (t.tv_usec - poll_start_t.tv_usec) +
                (t.tv_sec - poll_start_t.tv_sec)*1000000;       /* us */
        kern_load = (kern_load * hz) / 10000;                   /* 0..100 */
        if (kern_load > (100 - user_frac)) { /* try decrease ticks */
                if (poll_burst > 1)
                        poll_burst--;
        } else {
                if (poll_burst < poll_burst_max)
                        poll_burst++;
        }

        pending_polls--;
        if (pending_polls == 0) {       /* we are done */
                phase = 0;
        } else {
                /*
                 * Last cycle was long and caused us to miss one or more
                 * hardclock ticks. Restart processing again, but slightly
                 * reduce the burst size to prevent that this happens again.
                 */
                poll_burst -= (poll_burst / 8);
                if (poll_burst < 1)
                        poll_burst = 1;
                schednetisr(NETISR_POLL);
                phase = 6;
        }
out:
        crit_exit();
}

/*
 * netisr_poll is scheduled by schednetisr when appropriate, typically once
 * per tick.
 *
 * Note that the message is replied immediately in order to allow a new
 * ISR to be scheduled in the handler.
 *
 * XXX each registration should indicate whether it needs a critical
 * section to operate.
 */
/* ARGSUSED */
static void
netisr_poll(struct netmsg *msg)
{
        static int reg_frac_count;
        int i, cycles;
        enum poll_cmd arg = POLL_ONLY;

        lwkt_replymsg(&msg->nm_lmsg, 0);
        crit_enter();
        phase = 3;
        if (residual_burst == 0) { /* first call in this tick */
                microuptime(&poll_start_t);
                /*
                 * Check that paremeters are consistent with runtime
                 * variables. Some of these tests could be done at sysctl
                 * time, but the savings would be very limited because we
                 * still have to check against reg_frac_count and
                 * poll_each_burst. So, instead of writing separate sysctl
                 * handlers, we do all here.
                 */

                if (reg_frac > hz)
                        reg_frac = hz;
                else if (reg_frac < 1)
                        reg_frac = 1;
                if (reg_frac_count > reg_frac)
                        reg_frac_count = reg_frac - 1;
                if (reg_frac_count-- == 0) {
                        arg = POLL_AND_CHECK_STATUS;
                        reg_frac_count = reg_frac - 1;
                }
                if (poll_burst_max < MIN_POLL_BURST_MAX)
                        poll_burst_max = MIN_POLL_BURST_MAX;
                else if (poll_burst_max > MAX_POLL_BURST_MAX)
                        poll_burst_max = MAX_POLL_BURST_MAX;

                if (poll_each_burst < 1)
                        poll_each_burst = 1;
                else if (poll_each_burst > poll_burst_max)
                        poll_each_burst = poll_burst_max;

                residual_burst = poll_burst;
        }
        cycles = (residual_burst < poll_each_burst) ?
                residual_burst : poll_each_burst;
        residual_burst -= cycles;

        if (polling_enabled) {
                for (i = 0 ; i < poll_handlers ; i++) {
                        struct pollrec *p = &pr[i];
                        if ((p->ifp->if_flags & (IFF_UP|IFF_RUNNING|IFF_POLLING)) == (IFF_UP|IFF_RUNNING|IFF_POLLING)) {
                                if (lwkt_serialize_try(p->ifp->if_serializer)) {
                                        p->ifp->if_poll(p->ifp, arg, cycles);
                                        lwkt_serialize_exit(p->ifp->if_serializer);
                                }
                        }
                }
        } else {        /* unregister */
                for (i = 0 ; i < poll_handlers ; i++) {
                        struct pollrec *p = &pr[i];
                        if ((p->ifp->if_flags & IFF_POLLING) == 0)
                                continue;
                        /*
                         * Only call the interface deregistration
                         * function if the interface is still 
                         * running.
                         */
                        lwkt_serialize_enter(p->ifp->if_serializer);
                        p->ifp->if_flags &= ~IFF_POLLING;
                        if (p->ifp->if_flags & IFF_RUNNING)
                                p->ifp->if_poll(p->ifp, POLL_DEREGISTER, 1);
                        lwkt_serialize_exit(p->ifp->if_serializer);
                }
                residual_burst = 0;
                poll_handlers = 0;
        }
        schednetisr(NETISR_POLLMORE);
        phase = 4;
        crit_exit();
}

/*
 * Try to register routine for polling. Returns 1 if successful
 * (and polling should be enabled), 0 otherwise.
 *
 * Called from mainline code only, not called from an interrupt.
 */
int
ether_poll_register(struct ifnet *ifp)
{
        int rc;

        if (polling_enabled == 0) /* polling disabled, cannot register */
                return 0;
        if ((ifp->if_flags & IFF_UP) == 0)      /* must be up           */
                return 0;
        if (ifp->if_flags & IFF_POLLING)        /* already polling      */
                return 0;
        if (ifp->if_poll == NULL)               /* no polling support   */
                return 0;

        /*
         * Attempt to register.  Interlock with IFF_POLLING.
         */
        crit_enter();   /* XXX MP - not mp safe */
        lwkt_serialize_enter(ifp->if_serializer);
        ifp->if_flags |= IFF_POLLING;
        ifp->if_poll(ifp, POLL_REGISTER, 0);
        lwkt_serialize_exit(ifp->if_serializer);
        if ((ifp->if_flags & IFF_POLLING) == 0) {
                crit_exit();
                return 0;
        }

        /*
         * Check if there is room.  If there isn't, deregister.
         */
        if (poll_handlers >= POLL_LIST_LEN) {
                /*
                 * List full, cannot register more entries.
                 * This should never happen; if it does, it is probably a
                 * broken driver trying to register multiple times. Checking
                 * this at runtime is expensive, and won't solve the problem
                 * anyways, so just report a few times and then give up.
                 */
                static int verbose = 10 ;
                if (verbose >0) {
                        kprintf("poll handlers list full, "
                                "maybe a broken driver ?\n");
                        verbose--;
                }
                ifp->if_flags &= ~IFF_POLLING;
                lwkt_serialize_enter(ifp->if_serializer);
                ifp->if_poll(ifp, POLL_DEREGISTER, 0);
                lwkt_serialize_exit(ifp->if_serializer);
                rc = 0;
        } else {
                pr[poll_handlers].ifp = ifp;
                poll_handlers++;
                rc = 1;
        }
        crit_exit();
        return (rc);
}

/*
 * Remove interface from the polling list.  Occurs when polling is turned
 * off.  Called from mainline code only, not called from an interrupt.
 */
int
ether_poll_deregister(struct ifnet *ifp)
{
        int i;

        crit_enter();
        if (ifp == NULL || (ifp->if_flags & IFF_POLLING) == 0) {
                crit_exit();
                return 0;
        }
        for (i = 0 ; i < poll_handlers ; i++) {
                if (pr[i].ifp == ifp) /* found it */
                        break;
        }
        ifp->if_flags &= ~IFF_POLLING; /* found or not... */
        if (i == poll_handlers) {
                crit_exit();
                kprintf("ether_poll_deregister: ifp not found!!!\n");
                return 0;
        }
        poll_handlers--;
        if (i < poll_handlers) { /* Last entry replaces this one. */
                pr[i].ifp = pr[poll_handlers].ifp;
        }
        crit_exit();

        /*
         * Only call the deregistration function if the interface is still
         * in a run state.
         */
        if (ifp->if_flags & IFF_RUNNING) {
                lwkt_serialize_enter(ifp->if_serializer);
                ifp->if_poll(ifp, POLL_DEREGISTER, 1);
                lwkt_serialize_exit(ifp->if_serializer);
        }
        return (1);
}

void
emergency_poll_enable(const char *name)
{
        if (polling_enabled == 0) {
                polling_enabled = 1;
                kprintf("%s forced polling on\n", name);
        }
}