From b158577d787beaa6d098be3f180f947f7ad80b22 Mon Sep 17 00:00:00 2001 From: Alberto Faria Date: Thu, 1 Dec 2022 22:08:00 +0000 Subject: [PATCH] engines/libblkio: Add option libblkio_wait_mode It allows configuring how the engine waits for request completions, instead of always using a blocking blkioq_do_io() call. Signed-off-by: Alberto Faria Signed-off-by: Vincent Fu --- HOWTO.rst | 14 +++++- engines/libblkio.c | 117 ++++++++++++++++++++++++++++++++++++++++++--- fio.1 | 16 ++++++- 3 files changed, 139 insertions(+), 8 deletions(-) diff --git a/HOWTO.rst b/HOWTO.rst index 273b7a68..e9602f59 100644 --- a/HOWTO.rst +++ b/HOWTO.rst @@ -2337,7 +2337,8 @@ with the caveat that when used on the command line, they must come after the [libblkio] - Use poll queues. + Use poll queues. This is incompatible with + :option:`libblkio_wait_mode=eventfd `. [pvsync2] @@ -2895,6 +2896,17 @@ with the caveat that when used on the command line, they must come after the Submit trims as "write zeroes" requests instead of discard requests. +.. option:: libblkio_wait_mode=str : [libblkio] + + How to wait for completions: + + **block** (default) + Use a blocking call to ``blkioq_do_io()``. + **eventfd** + Use a blocking call to ``read()`` on the completion eventfd. + **loop** + Use a busy loop with a non-blocking call to ``blkioq_do_io()``. + I/O depth ~~~~~~~~~ diff --git a/engines/libblkio.c b/engines/libblkio.c index 66a9bd31..8a4828c3 100644 --- a/engines/libblkio.c +++ b/engines/libblkio.c @@ -24,6 +24,7 @@ struct fio_blkio_data { struct blkio *b; struct blkioq *q; + int completion_fd; /* -1 if not FIO_BLKIO_WAIT_MODE_EVENTFD */ bool has_mem_region; /* whether mem_region is valid */ struct blkio_mem_region mem_region; /* only if allocated by libblkio */ @@ -32,6 +33,12 @@ struct fio_blkio_data { struct blkio_completion *completions; }; +enum fio_blkio_wait_mode { + FIO_BLKIO_WAIT_MODE_BLOCK, + FIO_BLKIO_WAIT_MODE_EVENTFD, + FIO_BLKIO_WAIT_MODE_LOOP, +}; + struct fio_blkio_options { void *pad; /* option fields must not have offset 0 */ @@ -42,6 +49,7 @@ struct fio_blkio_options { unsigned int hipri; unsigned int vectored; unsigned int write_zeroes_on_trim; + enum fio_blkio_wait_mode wait_mode; }; static struct fio_option options[] = { @@ -100,6 +108,30 @@ static struct fio_option options[] = { .category = FIO_OPT_C_ENGINE, .group = FIO_OPT_G_LIBBLKIO, }, + { + .name = "libblkio_wait_mode", + .lname = "How to wait for completions", + .type = FIO_OPT_STR, + .off1 = offsetof(struct fio_blkio_options, wait_mode), + .help = "How to wait for completions", + .def = "block", + .posval = { + { .ival = "block", + .oval = FIO_BLKIO_WAIT_MODE_BLOCK, + .help = "Blocking blkioq_do_io()", + }, + { .ival = "eventfd", + .oval = FIO_BLKIO_WAIT_MODE_EVENTFD, + .help = "Blocking read() on the completion eventfd", + }, + { .ival = "loop", + .oval = FIO_BLKIO_WAIT_MODE_LOOP, + .help = "Busy loop with non-blocking blkioq_do_io()", + }, + }, + .category = FIO_OPT_C_ENGINE, + .group = FIO_OPT_G_LIBBLKIO, + }, { .name = NULL, }, @@ -231,12 +263,19 @@ err_blkio_destroy: */ static int fio_blkio_setup(struct thread_data *td) { + const struct fio_blkio_options *options = td->eo; struct blkio *b; int ret = 0; uint64_t capacity; assert(td->files_index == 1); + if (options->hipri && + options->wait_mode == FIO_BLKIO_WAIT_MODE_EVENTFD) { + log_err("fio: option hipri is incompatible with option libblkio_wait_mode=eventfd\n"); + return 1; + } + if (fio_blkio_create_and_connect(td, &b) != 0) return 1; @@ -258,6 +297,7 @@ static int fio_blkio_init(struct thread_data *td) { const struct fio_blkio_options *options = td->eo; struct fio_blkio_data *data; + int flags; /* * Request enqueueing is fast, and it's not possible to know exactly @@ -302,6 +342,28 @@ static int fio_blkio_init(struct thread_data *td) else data->q = blkio_get_queue(data->b, 0); + if (options->wait_mode == FIO_BLKIO_WAIT_MODE_EVENTFD) { + /* enable completion fd and make it blocking */ + blkioq_set_completion_fd_enabled(data->q, true); + data->completion_fd = blkioq_get_completion_fd(data->q); + + flags = fcntl(data->completion_fd, F_GETFL); + if (flags < 0) { + log_err("fio: fcntl(F_GETFL) failed: %s\n", + strerror(errno)); + goto err_blkio_destroy; + } + + if (fcntl(data->completion_fd, F_SETFL, + flags & ~O_NONBLOCK) != 0) { + log_err("fio: fcntl(F_SETFL) failed: %s\n", + strerror(errno)); + goto err_blkio_destroy; + } + } else { + data->completion_fd = -1; + } + /* Set data last so cleanup() does nothing if init() fails. */ td->io_ops_data = data; @@ -490,16 +552,59 @@ static enum fio_q_status fio_blkio_queue(struct thread_data *td, static int fio_blkio_getevents(struct thread_data *td, unsigned int min, unsigned int max, const struct timespec *t) { + const struct fio_blkio_options *options = td->eo; struct fio_blkio_data *data = td->io_ops_data; - int n; + int ret, n; + uint64_t event; + + switch (options->wait_mode) { + case FIO_BLKIO_WAIT_MODE_BLOCK: + n = blkioq_do_io(data->q, data->completions, (int)min, (int)max, + NULL); + if (n < 0) { + fio_blkio_log_err(blkioq_do_io); + return -1; + } + return n; + case FIO_BLKIO_WAIT_MODE_EVENTFD: + n = blkioq_do_io(data->q, data->completions, 0, (int)max, NULL); + if (n < 0) { + fio_blkio_log_err(blkioq_do_io); + return -1; + } + while (n < (int)min) { + ret = read(data->completion_fd, &event, sizeof(event)); + if (ret != sizeof(event)) { + log_err("fio: read() on the completion fd returned %d\n", + ret); + return -1; + } - n = blkioq_do_io(data->q, data->completions, (int)min, (int)max, NULL); - if (n < 0) { - fio_blkio_log_err(blkioq_do_io); + ret = blkioq_do_io(data->q, data->completions + n, 0, + (int)max - n, NULL); + if (ret < 0) { + fio_blkio_log_err(blkioq_do_io); + return -1; + } + + n += ret; + } + return n; + case FIO_BLKIO_WAIT_MODE_LOOP: + for (n = 0; n < (int)min; ) { + ret = blkioq_do_io(data->q, data->completions + n, 0, + (int)max - n, NULL); + if (ret < 0) { + fio_blkio_log_err(blkioq_do_io); + return -1; + } + + n += ret; + } + return n; + default: return -1; } - - return n; } static struct io_u *fio_blkio_event(struct thread_data *td, int event) diff --git a/fio.1 b/fio.1 index ad061caa..1a810214 100644 --- a/fio.1 +++ b/fio.1 @@ -2633,13 +2633,27 @@ properties depend on the libblkio version in use and are listed at \fIhttps://libblkio.gitlab.io/libblkio/blkio.html#properties\fR .TP .BI (libblkio)hipri -Use poll queues. +Use poll queues. This is incompatible with \fBlibblkio_wait_mode=eventfd\fR. .TP .BI (libblkio)libblkio_vectored Submit vectored read and write requests. .TP .BI (libblkio)libblkio_write_zeroes_on_trim Submit trims as "write zeroes" requests instead of discard requests. +.TP +.BI (libblkio)libblkio_wait_mode \fR=\fPstr +How to wait for completions: +.RS +.RS +.TP +.B block \fR(default) +Use a blocking call to \fBblkioq_do_io()\fR. +.TP +.B eventfd +Use a blocking call to \fBread()\fR on the completion eventfd. +.TP +.B loop +Use a busy loop with a non-blocking call to \fBblkioq_do_io()\fR. .SS "I/O depth" .TP .BI iodepth \fR=\fPint -- 2.25.1