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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V2] Switch to poll() in cxenstored's IO loop
Ian, ping?
On Tue, 2013-01-22 at 15:18 +0000, Wei Liu wrote:
> commit 14b82f52d40143019094727b8fa1aa3a111ffab3
> Author: Wei Liu <wei.liu2@xxxxxxxxxx>
> Date: Mon Jan 21 19:07:37 2013 +0000
>
> Switch to poll() in cxenstored's IO loop
>
> Poll() can support more file descriptors than select(). We've done this
> for
> xenconsoled, now do this for cxenstored as well.
>
> The code is taken from xenconsoled and modified to adapt to cxenstored.
>
> Updated:
> * reopen pipe if polling on reopen_log_pipe fails.
> * exit if polling on some critical fds fails.
>
> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
>
> diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
> index bd44645..b91704e 100644
> --- a/tools/xenstore/xenstored_core.c
> +++ b/tools/xenstore/xenstored_core.c
> @@ -19,7 +19,7 @@
>
> #include <sys/types.h>
> #include <sys/stat.h>
> -#include <sys/select.h>
> +#include <poll.h>
> #ifndef NO_SOCKETS
> #include <sys/socket.h>
> #include <sys/un.h>
> @@ -55,6 +55,12 @@
> #include "hashtable.h"
>
> extern xc_evtchn *xce_handle; /* in xenstored_domain.c */
> +static struct pollfd *xce_pollfd;
> +static struct pollfd *fds;
> +static unsigned int current_array_size;
> +static unsigned int nr_fds;
> +
> +#define ROUNDUP(_x, _w) (((unsigned long)(_x)+(1UL<<(_w))-1) &
> ~((1UL<<(_w))-1))
>
> static bool verbose = false;
> LIST_HEAD(connections);
> @@ -62,6 +68,7 @@ static int tracefd = -1;
> static bool recovery = true;
> static bool remove_local = true;
> static int reopen_log_pipe[2];
> +static struct pollfd *reopen_log_pipe0_pollfd;
> static char *tracefile = NULL;
> static TDB_CONTEXT *tdb_ctx = NULL;
>
> @@ -199,7 +206,7 @@ void trace_destroy(const void *data, const char *type)
> /**
> * Signal handler for SIGHUP, which requests that the trace log is reopened
> * (in the main loop). A single byte is written to reopen_log_pipe, to
> awaken
> - * the select() in the main loop.
> + * the poll() in the main loop.
> */
> static void trigger_reopen_log(int signal __attribute__((unused)))
> {
> @@ -279,15 +286,12 @@ static int destroy_conn(void *_conn)
>
> /* Flush outgoing if possible, but don't block. */
> if (!conn->domain) {
> - fd_set set;
> - struct timeval none;
> -
> - FD_ZERO(&set);
> - FD_SET(conn->fd, &set);
> - none.tv_sec = none.tv_usec = 0;
> + struct pollfd pfd;
> + pfd.fd = conn->fd;
> + pfd.events = POLLOUT;
>
> while (!list_empty(&conn->out_list)
> - && select(conn->fd+1, NULL, &set, NULL, &none) == 1)
> + && poll(&pfd, 1, 0) == 1)
> if (!write_messages(conn))
> break;
> close(conn->fd);
> @@ -300,52 +304,74 @@ static int destroy_conn(void *_conn)
> }
>
>
> -static void set_fd(int fd, fd_set *set, int *max)
> +static struct pollfd *set_fd(int fd, short events)
> {
> - if (fd < 0)
> - return;
> - FD_SET(fd, set);
> - if (fd > *max)
> - *max = fd;
> -}
> + struct pollfd *ret;
> + if (current_array_size < nr_fds + 1) {
> + struct pollfd *new_fds = NULL;
> + unsigned long newsize;
> +
> + /* Round up to 2^8 boundary, in practice this just
> + * make newsize larger than current_array_size.
> + */
> + newsize = ROUNDUP(nr_fds + 1, 8);
>
> + new_fds = realloc(fds, sizeof(struct pollfd)*newsize);
> + if (!new_fds)
> + goto fail;
> + fds = new_fds;
>
> -static int initialize_set(fd_set *inset, fd_set *outset, int sock, int
> ro_sock,
> - struct timeval **ptimeout)
> + memset(&fds[0] + current_array_size, 0,
> + sizeof(struct pollfd ) * (newsize-current_array_size));
> + current_array_size = newsize;
> + }
> +
> + fds[nr_fds].fd = fd;
> + fds[nr_fds].events = events;
> + ret = &fds[nr_fds];
> + nr_fds++;
> +
> + return ret;
> +fail:
> + syslog(LOG_ERR, "realloc failed, ignoring fd %d\n", fd);
> + return NULL;
> +}
> +
> +static void initialize_fds(int sock, struct pollfd **p_sock_pollfd,
> + int ro_sock, struct pollfd **p_ro_sock_pollfd,
> + int *ptimeout)
> {
> - static struct timeval zero_timeout = { 0 };
> struct connection *conn;
> - int max = -1;
>
> - *ptimeout = NULL;
> + memset(fds, 0, sizeof(struct pollfd) * current_array_size);
> + nr_fds = 0;
>
> - FD_ZERO(inset);
> - FD_ZERO(outset);
> + *ptimeout = -1;
>
> if (sock != -1)
> - set_fd(sock, inset, &max);
> + *p_sock_pollfd = set_fd(sock, POLLIN|POLLPRI);
> if (ro_sock != -1)
> - set_fd(ro_sock, inset, &max);
> + *p_ro_sock_pollfd = set_fd(ro_sock, POLLIN|POLLPRI);
> if (reopen_log_pipe[0] != -1)
> - set_fd(reopen_log_pipe[0], inset, &max);
> + reopen_log_pipe0_pollfd =
> + set_fd(reopen_log_pipe[0], POLLIN|POLLPRI);
>
> if (xce_handle != NULL)
> - set_fd(xc_evtchn_fd(xce_handle), inset, &max);
> + xce_pollfd = set_fd(xc_evtchn_fd(xce_handle), POLLIN|POLLPRI);
>
> list_for_each_entry(conn, &connections, list) {
> if (conn->domain) {
> if (domain_can_read(conn) ||
> (domain_can_write(conn) &&
> !list_empty(&conn->out_list)))
> - *ptimeout = &zero_timeout;
> + *ptimeout = 0;
> } else {
> - set_fd(conn->fd, inset, &max);
> + short events = POLLIN|POLLPRI;
> if (!list_empty(&conn->out_list))
> - FD_SET(conn->fd, outset);
> + events |= POLLOUT;
> + conn->pollfd = set_fd(conn->fd, events);
> }
> }
> -
> - return max;
> }
>
> /* Is child a subnode of parent, or equal? */
> @@ -1770,14 +1796,13 @@ int priv_domid = 0;
>
> int main(int argc, char *argv[])
> {
> - int opt, *sock, *ro_sock, max;
> - fd_set inset, outset;
> + int opt, *sock, *ro_sock;
> + struct pollfd *sock_pollfd = NULL, *ro_sock_pollfd = NULL;
> bool dofork = true;
> bool outputpid = false;
> bool no_domain_init = false;
> const char *pidfile = NULL;
> - int evtchn_fd = -1;
> - struct timeval *timeout;
> + int timeout;
>
> while ((opt = getopt_long(argc, argv, "DE:F:HNPS:t:T:RLVW:", options,
> NULL)) != -1) {
> @@ -1880,11 +1905,9 @@ int main(int argc, char *argv[])
>
> signal(SIGHUP, trigger_reopen_log);
>
> - if (xce_handle != NULL)
> - evtchn_fd = xc_evtchn_fd(xce_handle);
> -
> /* Get ready to listen to the tools. */
> - max = initialize_set(&inset, &outset, *sock, *ro_sock, &timeout);
> + initialize_fds(*sock, &sock_pollfd, *ro_sock, &ro_sock_pollfd,
> + &timeout);
>
> /* Tell the kernel we're up and running. */
> xenbus_notify_running();
> @@ -1893,27 +1916,55 @@ int main(int argc, char *argv[])
> for (;;) {
> struct connection *conn, *next;
>
> - if (select(max+1, &inset, &outset, NULL, timeout) < 0) {
> + if (poll(fds, nr_fds, timeout) < 0) {
> if (errno == EINTR)
> continue;
> - barf_perror("Select failed");
> + barf_perror("Poll failed");
> }
>
> - if (reopen_log_pipe[0] != -1 && FD_ISSET(reopen_log_pipe[0],
> &inset)) {
> - char c;
> - if (read(reopen_log_pipe[0], &c, 1) != 1)
> - barf_perror("read failed");
> - reopen_log();
> + if (reopen_log_pipe0_pollfd) {
> + if (reopen_log_pipe0_pollfd->revents &
> ~(POLLIN|POLLOUT|POLLPRI)) {
> + close(reopen_log_pipe[0]);
> + close(reopen_log_pipe[1]);
> + init_pipe(reopen_log_pipe);
> + } else if (reopen_log_pipe0_pollfd->revents & POLLIN) {
> + char c;
> + if (read(reopen_log_pipe[0], &c, 1) != 1)
> + barf_perror("read failed");
> + reopen_log();
> + }
> + reopen_log_pipe0_pollfd = NULL;
> }
>
> - if (*sock != -1 && FD_ISSET(*sock, &inset))
> - accept_connection(*sock, true);
> + if (sock_pollfd) {
> + if (sock_pollfd->revents & ~(POLLIN|POLLOUT|POLLPRI)) {
> + barf_perror("sock poll failed");
> + break;
> + } else if (sock_pollfd->revents & POLLIN) {
> + accept_connection(*sock, true);
> + sock_pollfd = NULL;
> + }
> + }
>
> - if (*ro_sock != -1 && FD_ISSET(*ro_sock, &inset))
> - accept_connection(*ro_sock, false);
> + if (ro_sock_pollfd) {
> + if (ro_sock_pollfd->revents &
> ~(POLLIN|POLLOUT|POLLPRI)) {
> + barf_perror("ro sock poll failed");
> + break;
> + } else if (ro_sock_pollfd->revents & POLLIN) {
> + accept_connection(*ro_sock, false);
> + ro_sock_pollfd = NULL;
> + }
> + }
>
> - if (evtchn_fd != -1 && FD_ISSET(evtchn_fd, &inset))
> - handle_event();
> + if (xce_pollfd) {
> + if (xce_pollfd->revents & ~(POLLIN|POLLOUT|POLLPRI)) {
> + barf_perror("xce_handle poll failed");
> + break;
> + } else if (xce_pollfd->revents & POLLIN) {
> + handle_event();
> + xce_pollfd = NULL;
> + }
> + }
>
> next = list_entry(connections.next, typeof(*conn), list);
> if (&next->list != &connections)
> @@ -1939,21 +1990,27 @@ int main(int argc, char *argv[])
> if (talloc_free(conn) == 0)
> continue;
> } else {
> - if (FD_ISSET(conn->fd, &inset))
> + if (conn->pollfd &&
> + !(conn->pollfd->revents &
> ~(POLLIN|POLLOUT|POLLPRI)) &&
> + (conn->pollfd->revents & POLLIN))
> handle_input(conn);
> if (talloc_free(conn) == 0)
> continue;
>
> talloc_increase_ref_count(conn);
> - if (FD_ISSET(conn->fd, &outset))
> + if (conn->pollfd &&
> + !(conn->pollfd->revents &
> ~(POLLIN|POLLOUT|POLLPRI)) &&
> + (conn->pollfd->revents & POLLOUT))
> handle_output(conn);
> if (talloc_free(conn) == 0)
> continue;
> +
> + conn->pollfd = NULL;
> }
> }
>
> - max = initialize_set(&inset, &outset, *sock, *ro_sock,
> - &timeout);
> + initialize_fds(*sock, &sock_pollfd, *ro_sock, &ro_sock_pollfd,
> + &timeout);
> }
> }
>
> diff --git a/tools/xenstore/xenstored_core.h b/tools/xenstore/xenstored_core.h
> index 492ca0d..f330a87 100644
> --- a/tools/xenstore/xenstored_core.h
> +++ b/tools/xenstore/xenstored_core.h
> @@ -60,6 +60,8 @@ struct connection
>
> /* The file descriptor we came in on. */
> int fd;
> + /* The pollfd corresponding to fd. */
> + struct pollfd *pollfd;
>
> /* Who am I? 0 for socket connections. */
> unsigned int id;
>
>
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