On 1/04/2014 7:49 AM, Edward Tomasz Napierala wrote:
> Author: trasz
> Date: Mon Mar 31 20:49:33 2014
> New Revision: 263978
> URL: http://svnweb.freebsd.org/changeset/base/263978
>
> Log:
> Make it possible to have multiple CTL worker threads. Leave the default
> of 1 for now.
>
> Sponsored by: The FreeBSD Foundation
>
> Modified:
> head/sys/cam/ctl/ctl.c
>
> Modified: head/sys/cam/ctl/ctl.c
> ==============================================================================
> --- head/sys/cam/ctl/ctl.c Mon Mar 31 19:58:08 2014 (r263977)
> +++ head/sys/cam/ctl/ctl.c Mon Mar 31 20:49:33 2014 (r263978)
> @@ -60,6 +60,7 @@ __FBSDID("$FreeBSD$");
> #include <sys/ioccom.h>
> #include <sys/queue.h>
> #include <sys/sbuf.h>
> +#include <sys/smp.h>
> #include <sys/endian.h>
> #include <sys/sysctl.h>
>
> @@ -320,6 +321,10 @@ static int ctl_is_single = 1;
> static int index_to_aps_page;
>
> SYSCTL_NODE(_kern_cam, OID_AUTO, ctl, CTLFLAG_RD, 0, "CAM Target Layer");
> +static int worker_threads = 1;
> +TUNABLE_INT("kern.cam.ctl.worker_threads", &worker_threads);
> +SYSCTL_INT(_kern_cam_ctl, OID_AUTO, worker_threads, CTLFLAG_RDTUN,
> + &worker_threads, 1, "Number of worker threads");
>
> /*
> * Serial number (0x80), device id (0x83), and supported pages (0x00)
> @@ -950,10 +955,7 @@ ctl_init(void)
> struct ctl_frontend *fe;
> struct ctl_lun *lun;
> uint8_t sc_id =0;
> -#if 0
> - int i;
> -#endif
> - int error, retval;
> + int i, error, retval;
> //int isc_retval;
>
> retval = 0;
> @@ -1085,17 +1087,35 @@ ctl_init(void)
> mtx_unlock(&softc->ctl_lock);
> #endif
>
> - error = kproc_create(ctl_work_thread, softc, &softc->work_thread, 0, 0,
> - "ctl_thrd");
> - if (error != 0) {
> - printf("error creating CTL work thread!\n");
> - mtx_lock(&softc->ctl_lock);
> - ctl_free_lun(lun);
> - mtx_unlock(&softc->ctl_lock);
> - ctl_pool_free(internal_pool);
> - ctl_pool_free(emergency_pool);
> - ctl_pool_free(other_pool);
> - return (error);
> + if (worker_threads > MAXCPU || worker_threads == 0) {
> + printf("invalid kern.cam.ctl.worker_threads value; "
> + "setting to 1");
> + worker_threads = 1;
> + } else if (worker_threads < 0) {
Why is it that the < 0 case is special enough that it gets the mp_ncpus
check below, but the == 0 and > MAXCPU cases don't?
> + if (mp_ncpus > 2) {
> + /*
> + * Using more than two worker threads actually hurts
> + * performance due to lock contention.
> + */
> + worker_threads = 2;
> + } else {
> + worker_threads = 1;
> + }
Are printf("Setting to N")'s worthwhile here as well given
worker_threads is set to a value that wasn't specified by the user, as
above?
> + }
> +
> + for (i = 0; i < worker_threads; i++) {
> + error = kproc_create(ctl_work_thread, softc,
> &softc->work_thread, 0, 0,
> + "ctl_thrd%d", i);
> + if (error != 0) {
> + printf("error creating CTL work thread!\n");
> + mtx_lock(&softc->ctl_lock);
> + ctl_free_lun(lun);
> + mtx_unlock(&softc->ctl_lock);
> + ctl_pool_free(internal_pool);
> + ctl_pool_free(emergency_pool);
> + ctl_pool_free(other_pool);
> + return (error);
> + }
> }
> if (bootverbose)
> printf("ctl: CAM Target Layer loaded\n");
> @@ -12991,7 +13011,11 @@ ctl_work_thread(void *arg)
> if (io != NULL) {
> STAILQ_REMOVE_HEAD(&softc->rtr_queue, links);
> mtx_unlock(&softc->ctl_lock);
> - goto execute;
> + retval = ctl_scsiio(&io->scsiio);
> + if (retval != CTL_RETVAL_COMPLETE)
> + CTL_DEBUG_PRINT(("ctl_scsiio
> failed\n"));
> + mtx_lock(&softc->ctl_lock);
> + continue;
> }
> }
> io = (union ctl_io *)STAILQ_FIRST(&softc->incoming_queue);
> @@ -13022,19 +13046,6 @@ ctl_work_thread(void *arg)
>
> /* Back to the top of the loop to see what woke us up. */
> continue;
> -
> -execute:
> - retval = ctl_scsiio(&io->scsiio);
> - switch (retval) {
> - case CTL_RETVAL_COMPLETE:
> - break;
> - default:
> - /*
> - * Probably need to make sure this doesn't happen.
> - */
> - break;
> - }
> - mtx_lock(&softc->ctl_lock);
> }
> }
>
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