[libvirt RFC v3 12/19] multifd-helper: new helper for parallel save/restore
Claudio Fontana
cfontana at suse.de
Tue Apr 26 17:01:58 UTC 2022
On 4/26/22 6:47 PM, Claudio Fontana wrote:
> For the save direction, this helper listens on a unix socket
> which QEMU connects to for multifd migration to files.
>
> For the restore direction, this helper connects to a unix socket
> QEMU listens at for multifd migration from files.
>
> The file descriptors are passed as command line parameters.
>
> Signed-off-by: Claudio Fontana <cfontana at suse.de>
> ---
> src/libvirt_private.syms | 1 +
> src/util/meson.build | 13 ++
> src/util/multifd-helper.c | 250 ++++++++++++++++++++++++++++++++++++++
> src/util/virthread.c | 5 +
> src/util/virthread.h | 1 +
> 5 files changed, 270 insertions(+)
> create mode 100644 src/util/multifd-helper.c
>
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 97bfca906b..5f2bee985e 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -3427,6 +3427,7 @@ virThreadCreateFull;
> virThreadID;
> virThreadIsSelf;
> virThreadJoin;
> +virThreadJoinRet;
> virThreadMaxName;
> virThreadSelf;
> virThreadSelfID;
> diff --git a/src/util/meson.build b/src/util/meson.build
> index 58001a1699..8ea74ff9e8 100644
> --- a/src/util/meson.build
> +++ b/src/util/meson.build
> @@ -179,6 +179,12 @@ io_helper_sources = [
> 'runio.h',
> ]
>
> +multifd_helper_sources = [
> + 'multifd-helper.c',
> + 'runio.c',
> + 'runio.h',
> +]
> +
> virt_util_lib = static_library(
> 'virt_util',
> [
> @@ -216,6 +222,13 @@ if conf.has('WITH_LIBVIRTD')
> dtrace_gen_headers,
> ],
> }
> + virt_helpers += {
> + 'name': 'libvirt_multifd_helper',
> + 'sources': [
> + files(multifd_helper_sources),
> + dtrace_gen_headers,
> + ],
> + }
> endif
>
> util_inc_dir = include_directories('.')
> diff --git a/src/util/multifd-helper.c b/src/util/multifd-helper.c
> new file mode 100644
> index 0000000000..37e61a3a4d
> --- /dev/null
> +++ b/src/util/multifd-helper.c
> @@ -0,0 +1,250 @@
> +/*
> + * multifd-helper.c: listens on Unix socket to perform I/O to multiple files
> + *
> + * Copyright (C) 2022 SUSE LLC
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library. If not, see
> + * <http://www.gnu.org/licenses/>.
> + *
> + * This has been written to support QEMU multifd migration to file,
> + * allowing better use of cpu resources to speed up the save/restore.
> + */
> +
> +#include <config.h>
> +
> +#include <unistd.h>
> +#include <fcntl.h>
> +#include <stdlib.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <sys/socket.h>
> +#include <sys/un.h>
> +
> +#include "virthread.h"
> +#include "virfile.h"
> +#include "virerror.h"
> +#include "virstring.h"
> +#include "virgettext.h"
> +#include "runio.h"
> +
> +#define VIR_FROM_THIS VIR_FROM_STORAGE
> +
> +typedef struct _multiFdConnData multiFdConnData;
> +struct _multiFdConnData {
> + int clientfd;
> + int filefd;
> + int oflags;
> + const char *path;
> + virThread tid;
> +
> + off_t total;
> +};
> +
> +typedef struct _multiFdThreadArgs multiFdThreadArgs;
> +struct _multiFdThreadArgs {
> + int nchannels;
> + multiFdConnData *conn; /* contains main fd + nchannels */
> + const char *sun_path; /* unix socket name to use for the server */
> + struct sockaddr_un serv_addr;
> +
> + off_t total;
> +};
> +
> +static void clientThreadFunc(void *a)
> +{
> + multiFdConnData *c = a;
> + c->total = runIO(c->path, c->filefd, c->oflags, c->clientfd, c->clientfd);
> +}
> +
> +static off_t waitClientThreads(multiFdConnData *conn, int n)
> +{
> + int i;
> + off_t total = 0;
> + for (i = 0; i < n; i++) {
> + multiFdConnData *c = &conn[i];
> + if (virThreadJoinRet(&c->tid) < 0) {
> + total = -1;
> + } else if (total >= 0) {
> + total += c->total;
> + }
> + if (VIR_CLOSE(c->clientfd) < 0) {
> + total = -1;
> + }
> + }
> + return total;
> +}
> +
> +static void loadThreadFunc(void *a)
> +{
> + multiFdThreadArgs *args = a;
> + int i;
> + args->total = -1;
> +
> + for (i = 0; i < args->nchannels + 1; i++) {
> + /* Perform outgoing connections */
> + multiFdConnData *c = &args->conn[i];
> + c->clientfd = socket(AF_UNIX, SOCK_STREAM, 0);
> + if (c->clientfd < 0) {
> + virReportSystemError(errno, "%s", _("loadThread: socket() failed"));
> + goto cleanup;
> + }
> + if (connect(c->clientfd, (const struct sockaddr *)&args->serv_addr,
> + sizeof(struct sockaddr_un)) < 0) {
> + virReportSystemError(errno, "%s", _("loadThread: connect() failed"));
> + goto cleanup;
> + }
> + if (virThreadCreate(&c->tid, true, &clientThreadFunc, c) < 0) {
> + virReportSystemError(errno, "%s", _("loadThread: client thread creation failed"));
> + goto cleanup;
> + }
> + }
> + args->total = waitClientThreads(args->conn, args->nchannels + 1);
> +
> + cleanup:
> + for (i = 0; i < args->nchannels + 1; i++) {
> + multiFdConnData *c = &args->conn[i];
> + VIR_FORCE_CLOSE(c->clientfd);
> + }
> +}
> +
> +static void saveThreadFunc(void *a)
> +{
> + multiFdThreadArgs *args = a;
> + int i;
> + const char buf[1] = {'R'};
> + int sockfd;
> +
> + if ((sockfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
> + virReportSystemError(errno, "%s", _("saveThread: socket() failed"));
> + return;
> + }
> + unlink(args->sun_path);
> + if (bind(sockfd, (struct sockaddr *)&args->serv_addr, sizeof(args->serv_addr)) < 0) {
> + virReportSystemError(errno, "%s", _("saveThread: bind() failed"));
> + goto cleanup;
> + }
> + if (listen(sockfd, args->nchannels + 1) < 0) {
> + virReportSystemError(errno, "%s", _("saveThread: listen() failed"));
> + goto cleanup;
> + }
> +
> + /* signal that the server is ready */
> + if (safewrite(STDOUT_FILENO, &buf, 1) != 1) {
> + virReportSystemError(errno, "%s", _("saveThread: safewrite failed"));
> + goto cleanup;
> + }
> +
> + for (i = 0; i < args->nchannels + 1; i++) {
> + /* Wait for incoming connection. */
> + multiFdConnData *c = &args->conn[i];
> + if ((c->clientfd = accept(sockfd, NULL, NULL)) < 0) {
> + virReportSystemError(errno, "%s", _("saveThread: accept() failed"));
> + goto cleanup;
> + }
> + if (virThreadCreate(&c->tid, true, &clientThreadFunc, c) < 0) {
> + virReportSystemError(errno, "%s", _("saveThread: client thread creation failed"));
> + goto cleanup;
> + }
> + }
> +
> + args->total = waitClientThreads(args->conn, args->nchannels + 1);
> +
> + cleanup:
> + for (i = 0; i < args->nchannels + 1; i++) {
> + multiFdConnData *c = &args->conn[i];
> + VIR_FORCE_CLOSE(c->clientfd);
> + }
> + if (VIR_CLOSE(sockfd) < 0)
> + args->total = -1;
> +}
> +
> +static const char *program_name;
> +
> +G_GNUC_NORETURN static void
> +usage(int status)
> +{
> + if (status) {
> + fprintf(stderr, _("%s: try --help for more details"), program_name);
> + } else {
> + fprintf(stderr, _("Usage: %s UNIX_SOCNAME N MAINFD FD0 FD1 ... FDn"), program_name);
> + }
> + exit(status);
> +}
> +
> +int
> +main(int argc, char **argv)
> +{
> + virThread tid;
> + virThreadFunc func = saveThreadFunc;
> + multiFdThreadArgs args = { 0 };
> + int i;
> +
> + sleep(10);
This of course should not be there, something handy during debugging only.
> +
> + program_name = argv[0];
> +
> + if (virGettextInitialize() < 0 ||
> + virErrorInitialize() < 0) {
> + fprintf(stderr, _("%s: initialization failed"), program_name);
> + exit(EXIT_FAILURE);
> + }
> +
> + if (argc > 1 && STREQ(argv[1], "--help"))
> + usage(EXIT_SUCCESS);
> + if (argc < 4)
> + usage(EXIT_FAILURE);
> +
> + args.sun_path = argv[1];
> + if (virStrToLong_i(argv[2], NULL, 10, &args.nchannels) < 0)
> + fprintf(stderr, _("%s: malformed number of channels N %s"), program_name, argv[2]);
> +
> + if (argc < 4 + args.nchannels)
> + usage(EXIT_FAILURE);
> +
> + args.conn = g_new0(multiFdConnData, args.nchannels + 1);
> +
> + for (i = 3; i < 3 + args.nchannels + 1; i++) {
> + multiFdConnData *c = &args.conn[i - 3];
> +
> + if (virStrToLong_i(argv[i], NULL, 10, &c->filefd) < 0) {
> + fprintf(stderr, _("%s: malformed FD %s"), program_name, argv[i]);
> + usage(EXIT_FAILURE);
> + }
> +#ifndef F_GETFL
> +#error "multifd-helper requires F_GETFL parameter of fcntl"
> +#endif
> + c->oflags = fcntl(c->filefd, F_GETFL);
> + if ((c->oflags & O_ACCMODE) == O_RDONLY) {
> + func = loadThreadFunc;
> + }
> + }
> +
> + /* initialize server address structure */
> + memset(&args.serv_addr, 0, sizeof(args.serv_addr));
> + args.serv_addr.sun_family = AF_UNIX;
> + strncpy(args.serv_addr.sun_path, args.sun_path, sizeof(args.serv_addr.sun_path) - 1);
> +
> + if (virThreadCreate(&tid, true, func, &args) < 0) {
> + virReportSystemError(errno, _("%s: failed to create server thread"), program_name);
> + exit(EXIT_FAILURE);
> + }
> +
> + if (virThreadJoinRet(&tid) < 0)
> + exit(EXIT_FAILURE);
> +
> + if (args.total < 0)
> + exit(EXIT_FAILURE);
> +
> + exit(EXIT_SUCCESS);
> +}
> diff --git a/src/util/virthread.c b/src/util/virthread.c
> index 5422bb74fd..0f6c6a68fa 100644
> --- a/src/util/virthread.c
> +++ b/src/util/virthread.c
> @@ -348,6 +348,11 @@ void virThreadJoin(virThread *thread)
> pthread_join(thread->thread, NULL);
> }
>
> +int virThreadJoinRet(virThread *thread)
> +{
> + return pthread_join(thread->thread, NULL);
> +}
> +
> void virThreadCancel(virThread *thread)
> {
> pthread_cancel(thread->thread);
> diff --git a/src/util/virthread.h b/src/util/virthread.h
> index 23abe0b6c9..5cecb9bd8a 100644
> --- a/src/util/virthread.h
> +++ b/src/util/virthread.h
> @@ -89,6 +89,7 @@ int virThreadCreateFull(virThread *thread,
> void virThreadSelf(virThread *thread);
> bool virThreadIsSelf(virThread *thread);
> void virThreadJoin(virThread *thread);
> +int virThreadJoinRet(virThread *thread);
>
> size_t virThreadMaxName(void);
>
>
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