40ea77a036
When safety requirements are met, it allows to avoid passing I/O requests to GEOM g_up/g_down thread, executing them directly in the caller context. That allows to avoid CPU bottlenecks in g_up/g_down threads, plus avoid several context switches per I/O. The defined now safety requirements are: - caller should not hold any locks and should be reenterable; - callee should not depend on GEOM dual-threaded concurency semantics; - on the way down, if request is unmapped while callee doesn't support it, the context should be sleepable; - kernel thread stack usage should be below 50%. To keep compatibility with GEOM classes not meeting above requirements new provider and consumer flags added: - G_CF_DIRECT_SEND -- consumer code meets caller requirements (request); - G_CF_DIRECT_RECEIVE -- consumer code meets callee requirements (done); - G_PF_DIRECT_SEND -- provider code meets caller requirements (done); - G_PF_DIRECT_RECEIVE -- provider code meets callee requirements (request). Capable GEOM class can set them, allowing direct dispatch in cases where it is safe. If any of requirements are not met, request is queued to g_up or g_down thread same as before. Such GEOM classes were reviewed and updated to support direct dispatch: CONCAT, DEV, DISK, GATE, MD, MIRROR, MULTIPATH, NOP, PART, RAID, STRIPE, VFS, ZERO, ZFS::VDEV, ZFS::ZVOL, all classes based on g_slice KPI (LABEL, MAP, FLASHMAP, etc). To declare direct completion capability disk(9) KPI got new flag equivalent to G_PF_DIRECT_SEND -- DISKFLAG_DIRECT_COMPLETION. da(4) and ada(4) disk drivers got it set now thanks to earlier CAM locking work. This change more then twice increases peak block storage performance on systems with manu CPUs, together with earlier CAM locking changes reaching more then 1 million IOPS (512 byte raw reads from 16 SATA SSDs on 4 HBAs to 256 user-level threads). Sponsored by: iXsystems, Inc. MFC after: 2 months
144 lines
3.9 KiB
C
144 lines
3.9 KiB
C
/*-
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* Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/bio.h>
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#include <sys/kernel.h>
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#include <sys/limits.h>
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#include <sys/malloc.h>
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#include <sys/queue.h>
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#include <sys/sysctl.h>
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#include <sys/systm.h>
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#include <geom/geom.h>
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#define G_ZERO_CLASS_NAME "ZERO"
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static int g_zero_clear_sysctl(SYSCTL_HANDLER_ARGS);
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SYSCTL_DECL(_kern_geom);
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static SYSCTL_NODE(_kern_geom, OID_AUTO, zero, CTLFLAG_RW, 0,
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"GEOM_ZERO stuff");
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static int g_zero_clear = 1;
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SYSCTL_PROC(_kern_geom_zero, OID_AUTO, clear, CTLTYPE_INT|CTLFLAG_RW,
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&g_zero_clear, 0, g_zero_clear_sysctl, "I", "Clear read data buffer");
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static int g_zero_byte = 0;
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SYSCTL_INT(_kern_geom_zero, OID_AUTO, byte, CTLFLAG_RW, &g_zero_byte, 0,
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"Byte (octet) value to clear the buffers with");
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static struct g_provider *gpp;
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static int
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g_zero_clear_sysctl(SYSCTL_HANDLER_ARGS)
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{
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int error;
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error = sysctl_handle_int(oidp, &g_zero_clear, 0, req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (gpp == NULL)
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return (ENXIO);
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if (g_zero_clear)
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gpp->flags &= ~G_PF_ACCEPT_UNMAPPED;
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else
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gpp->flags |= G_PF_ACCEPT_UNMAPPED;
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return (0);
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}
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static void
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g_zero_start(struct bio *bp)
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{
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int error = ENXIO;
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switch (bp->bio_cmd) {
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case BIO_READ:
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if (g_zero_clear && (bp->bio_flags & BIO_UNMAPPED) == 0)
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memset(bp->bio_data, g_zero_byte, bp->bio_length);
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/* FALLTHROUGH */
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case BIO_DELETE:
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case BIO_WRITE:
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bp->bio_completed = bp->bio_length;
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error = 0;
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break;
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case BIO_GETATTR:
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default:
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error = EOPNOTSUPP;
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break;
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}
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g_io_deliver(bp, error);
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}
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static void
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g_zero_init(struct g_class *mp)
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{
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struct g_geom *gp;
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struct g_provider *pp;
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g_topology_assert();
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gp = g_new_geomf(mp, "gzero");
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gp->start = g_zero_start;
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gp->access = g_std_access;
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gpp = pp = g_new_providerf(gp, "%s", gp->name);
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pp->flags |= G_PF_DIRECT_SEND | G_PF_DIRECT_RECEIVE;
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if (!g_zero_clear)
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pp->flags |= G_PF_ACCEPT_UNMAPPED;
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pp->mediasize = 1152921504606846976LLU;
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pp->sectorsize = 512;
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g_error_provider(pp, 0);
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}
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static int
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g_zero_destroy_geom(struct gctl_req *req __unused, struct g_class *mp __unused,
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struct g_geom *gp)
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{
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struct g_provider *pp;
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g_topology_assert();
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if (gp == NULL)
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return (0);
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pp = LIST_FIRST(&gp->provider);
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if (pp == NULL)
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return (0);
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if (pp->acr > 0 || pp->acw > 0 || pp->ace > 0)
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return (EBUSY);
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gpp = NULL;
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g_wither_geom(gp, ENXIO);
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return (0);
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}
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static struct g_class g_zero_class = {
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.name = G_ZERO_CLASS_NAME,
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.version = G_VERSION,
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.init = g_zero_init,
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.destroy_geom = g_zero_destroy_geom
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};
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DECLARE_GEOM_CLASS(g_zero_class, g_zero);
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