From nobody Tue Nov 11 16:07:41 2025 X-Original-To: dev-commits-src-main@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4d5Wdn2lDMz6GfPk; Tue, 11 Nov 2025 16:07:41 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R12" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4d5Wdn1zzmz3Yjj; Tue, 11 Nov 2025 16:07:41 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1762877261; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=F9Vgeu6e+PSEK12x0kRQt8ondOFhb9lKzWY+6wEq7Dg=; b=l/HpXWOOToCtpIiQx4xr9o2jxqStTBeEGIHOYfkcXep97oNjfqx+6UIREm/fg+60vqv4jW d6WfgvBdl3XGyBmHSChb4I+O8kg/ZDJjS+3StoQM6qYc4yyYyr5YwPycWylwMLdlPoqkZc N/E14vukqIRCnPybsKutcUuYmR5dFcm3zxvc4lYUfoBR6/+aYDWm2EStrbytJw/5zKh/Ex 9/+LYkuZVgfKMpmq8FLEqF0SdfSzZ98RFiKoJjTxzYeb0nG/h/cBJZg+uOaYsQsB0NK+vD Sm68DzSlXRdPcVlmYllEo0415MrcZSWufs+mADOUZF32Dgs2BY6BXY0J6ZkMsA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1762877261; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=F9Vgeu6e+PSEK12x0kRQt8ondOFhb9lKzWY+6wEq7Dg=; b=gl+rlOIQNBoDO7vT00DWiAUlcTZ+TrgH5kjHy3ykqXSAkvIW3I13BVqsvlR//v7J83yFR8 2olgAkiuXpF/RbfTxrfl677qKRH5W5ChC177xV317r2PUZarzdBoZnfSeocThAuv0cJRO5 FeY46vfI7ZUZ5HcU4OkCSUzxD6A9J+M8bfWV/72yIP/+HWP/LS0y7DDge7hpvDRZzqQ9cd v+/zThkp24BCT8kM27Ph5MIo5YeYTfiEl7NmvQCpaIgN02qDy22Oc6ZhhCgfr8HcCiYybw /xHhPFm2djz/KBrN8AbIL2XE9lTLEoDZarbUKY7syPEJL8sGy4U0EMBy3j3dpA== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1762877261; a=rsa-sha256; cv=none; b=Dpci213l1Hsv2nSbqQIugwDPIXYjYAqzFy/XL2khcDMFpsUBgvwVIbWJW+bRmll5LNkkTt x7Sc361i68mZime8iq/LbVXiHWBivbCb1/DZcqaI+/S1/299BqzzwBVfKlYhjSQrH4nlbB qsoKLnz0V8ZK8xhGaS9I/63FHck4EaCC4Ut7OiHwhc7MHIa6g4csEQuENrhSc3HagGjOlH XRT0CKONOuBsnnIPZV8Fs0YVlEBZUNYFZxPHb5qxMwwREKhxCzs9AjS+a3BlpCJvONzIAc 19nA/eWYpvmi1vqAY4rP4jcBU6miqaaX8n99xNuCzhh7C8PX3wMHBIiVS5d+KQ== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4d5Wdn1R6Zz19vM; Tue, 11 Nov 2025 16:07:41 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 5ABG7f6F088848; Tue, 11 Nov 2025 16:07:41 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 5ABG7flM088845; Tue, 11 Nov 2025 16:07:41 GMT (envelope-from git) Date: Tue, 11 Nov 2025 16:07:41 GMT Message-Id: <202511111607.5ABG7flM088845@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Mateusz Piotrowski <0mp@FreeBSD.org> Subject: git: d01183fddf37 - main - geom/zero: Add support for unmapped I/O List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-main@freebsd.org Sender: owner-dev-commits-src-main@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: 0mp X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: d01183fddf37b15da7ab3d69039e7759ae144451 Auto-Submitted: auto-generated The branch main has been updated by 0mp: URL: https://cgit.FreeBSD.org/src/commit/?id=d01183fddf37b15da7ab3d69039e7759ae144451 commit d01183fddf37b15da7ab3d69039e7759ae144451 Author: Mateusz Piotrowski <0mp@FreeBSD.org> AuthorDate: 2025-09-26 07:08:30 +0000 Commit: Mateusz Piotrowski <0mp@FreeBSD.org> CommitDate: 2025-11-11 16:06:59 +0000 geom/zero: Add support for unmapped I/O This patch adds support for unmapped I/O to gzero(4). Let's consider the following script to illustrate the change in gzero(4)'s behavior: ``` dd="dd if=/dev/gzero of=/dev/null bs=512 count=100000" dtrace -q -c "$dd" -n ' fbt::pmap_qenter:entry, fbt::uiomove_fromphys:entry, fbt::memset:entry /execname == "dd"/ { @[probefunc] = count(); } ' ``` Let's run that script 4 times: ``` ==> 1: unmapped I/O not supported (fallback to mapped I/O), kern.geom.zero.clear=1 51200000 bytes transferred in 1.795809 secs (28510829 bytes/sec) pmap_qenter 100000 memset 400011 ==> 2: unmapped I/O not supported (fallback to mapped I/O), kern.geom.zero.clear=0 51200000 bytes transferred in 0.701079 secs (73030337 bytes/sec) memset 300011 ==> 3: unmapped I/O supported, kern.geom.zero.clear=1 51200000 bytes transferred in 0.771680 secs (66348750 bytes/sec) uiomove_fromphys 100000 memset 300011 ==> 4: unmapped I/O supported, kern.geom.zero.clear=0 51200000 bytes transferred in 0.621303 secs (82407407 bytes/sec) memset 300011 ``` If kern.geom.zero.clear=0, then nothing really changes as no copying takes place. Otherwise, we see by adding unmapped I/O support we avoid calls to pmap_qenter(), which was called by GEOM to turn unmapped I/O requests into mapped ones before passing them for processing to gzero(4). Reviewed by: bnovkov, markj Approved by: bnovkov (mentor), markj (mentor) MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D52998 --- sys/geom/zero/g_zero.c | 82 ++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 63 insertions(+), 19 deletions(-) diff --git a/sys/geom/zero/g_zero.c b/sys/geom/zero/g_zero.c index 7952147d660a..25d462a9f918 100644 --- a/sys/geom/zero/g_zero.c +++ b/sys/geom/zero/g_zero.c @@ -3,6 +3,7 @@ * * Copyright (c) 2005 Pawel Jakub Dawidek * All rights reserved. + * Copyright (c) 2025 Mateusz Piotrowski <0mp@FreeBSD.org> * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions @@ -34,53 +35,97 @@ #include #include #include +#include +#include #include #define G_ZERO_CLASS_NAME "ZERO" -static int g_zero_clear_sysctl(SYSCTL_HANDLER_ARGS); +static int g_zero_byte_sysctl(SYSCTL_HANDLER_ARGS); SYSCTL_DECL(_kern_geom); static SYSCTL_NODE(_kern_geom, OID_AUTO, zero, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, "GEOM_ZERO stuff"); static int g_zero_clear = 1; -SYSCTL_PROC(_kern_geom_zero, OID_AUTO, clear, - CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, &g_zero_clear, 0, - g_zero_clear_sysctl, "I", +SYSCTL_INT(_kern_geom_zero, OID_AUTO, clear, + CTLFLAG_RWTUN, &g_zero_clear, 0, "Clear read data buffer"); static int g_zero_byte = 0; -SYSCTL_INT(_kern_geom_zero, OID_AUTO, byte, CTLFLAG_RWTUN, &g_zero_byte, 0, +static uint8_t g_zero_buffer[PAGE_SIZE]; +SYSCTL_PROC(_kern_geom_zero, OID_AUTO, byte, + CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, &g_zero_byte, 0, + g_zero_byte_sysctl, "I", "Byte (octet) value to clear the buffers with"); static struct g_provider *gpp; static int -g_zero_clear_sysctl(SYSCTL_HANDLER_ARGS) +g_zero_byte_sysctl(SYSCTL_HANDLER_ARGS) { int error; - error = sysctl_handle_int(oidp, &g_zero_clear, 0, req); + // XXX: Confirm that this is called on module load as well. + // XXX: Shouldn't we lock here to avoid changing the byte value if the + // driver is in the process of handling I/O? + error = sysctl_handle_int(oidp, &g_zero_byte, 0, req); if (error != 0 || req->newptr == NULL) return (error); - if (gpp == NULL) - return (ENXIO); - if (g_zero_clear) - gpp->flags &= ~G_PF_ACCEPT_UNMAPPED; - else - gpp->flags |= G_PF_ACCEPT_UNMAPPED; + memset(g_zero_buffer, g_zero_byte, PAGE_SIZE); return (0); } +static void +g_zero_fill_pages(struct bio *bp) +{ + struct iovec aiovec; + struct uio auio; + size_t length; + vm_offset_t offset; + + aiovec.iov_base = g_zero_buffer; + aiovec.iov_len = PAGE_SIZE; + auio.uio_iov = &aiovec; + auio.uio_iovcnt = 1; + auio.uio_offset = 0; + auio.uio_segflg = UIO_SYSSPACE; + auio.uio_rw = UIO_WRITE; + auio.uio_td = curthread; + + /* + * To handle the unmapped I/O request, we need to fill the pages in the + * bp->bio_ma array with the g_zero_byte value. However, instead of + * setting every byte individually, we use uiomove_fromphys() to fill a + * page at a time with g_zero_buffer. + */ + bp->bio_resid = bp->bio_length; + offset = bp->bio_ma_offset & PAGE_MASK; + for (int i = 0; i < bp->bio_ma_n && bp->bio_resid > 0; i++) { + length = MIN(PAGE_SIZE - offset, bp->bio_resid); + auio.uio_resid = length; + + (void)uiomove_fromphys(&bp->bio_ma[i], offset, length, &auio); + + offset = 0; + bp->bio_resid -= length; + } +} + + static void g_zero_start(struct bio *bp) { - int error = ENXIO; + int error; switch (bp->bio_cmd) { case BIO_READ: - if (g_zero_clear && (bp->bio_flags & BIO_UNMAPPED) == 0) - memset(bp->bio_data, g_zero_byte, bp->bio_length); + if (g_zero_clear) { + if ((bp->bio_flags & BIO_UNMAPPED) != 0) + g_zero_fill_pages(bp); + else + memset(bp->bio_data, g_zero_byte, + bp->bio_length); + } /* FALLTHROUGH */ case BIO_DELETE: case BIO_WRITE: @@ -106,9 +151,8 @@ g_zero_init(struct g_class *mp) gp->start = g_zero_start; gp->access = g_std_access; gpp = pp = g_new_providerf(gp, "%s", gp->name); - pp->flags |= G_PF_DIRECT_SEND | G_PF_DIRECT_RECEIVE; - if (!g_zero_clear) - pp->flags |= G_PF_ACCEPT_UNMAPPED; + pp->flags |= G_PF_ACCEPT_UNMAPPED | G_PF_DIRECT_SEND | + G_PF_DIRECT_RECEIVE; pp->mediasize = 1152921504606846976LLU; pp->sectorsize = 512; g_error_provider(pp, 0);