From b1bd09b593ddd4043c6217321c7135c0c580edc0 Mon Sep 17 00:00:00 2001 From: Alberto Faria Date: Thu, 1 Dec 2022 22:08:01 +0000 Subject: [PATCH] engines/libblkio: Add option libblkio_force_enable_completion_eventfd When set, the queue's completion fd is enabled even when it isn't used, i.e., even if option libblkio_wait_mode is _not_ set to "eventfd". Depending on the libblkio driver, this can have an impact on performance. This option allows evaluating that overhead. Signed-off-by: Alberto Faria Signed-off-by: Vincent Fu --- HOWTO.rst | 9 ++++++++- engines/libblkio.c | 21 +++++++++++++++++++-- fio.1 | 10 +++++++++- 3 files changed, 36 insertions(+), 4 deletions(-) diff --git a/HOWTO.rst b/HOWTO.rst index e9602f59..1cea16c4 100644 --- a/HOWTO.rst +++ b/HOWTO.rst @@ -2338,7 +2338,8 @@ with the caveat that when used on the command line, they must come after the [libblkio] Use poll queues. This is incompatible with - :option:`libblkio_wait_mode=eventfd `. + :option:`libblkio_wait_mode=eventfd ` and + :option:`libblkio_force_enable_completion_eventfd`. [pvsync2] @@ -2907,6 +2908,12 @@ with the caveat that when used on the command line, they must come after the **loop** Use a busy loop with a non-blocking call to ``blkioq_do_io()``. +.. option:: libblkio_force_enable_completion_eventfd : [libblkio] + + Enable the queue's completion eventfd even when unused. This may impact + performance. The default is to enable it only if + :option:`libblkio_wait_mode=eventfd `. + I/O depth ~~~~~~~~~ diff --git a/engines/libblkio.c b/engines/libblkio.c index 8a4828c3..7f5dcf36 100644 --- a/engines/libblkio.c +++ b/engines/libblkio.c @@ -24,7 +24,7 @@ struct fio_blkio_data { struct blkio *b; struct blkioq *q; - int completion_fd; /* -1 if not FIO_BLKIO_WAIT_MODE_EVENTFD */ + int completion_fd; /* may be -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 */ @@ -50,6 +50,7 @@ struct fio_blkio_options { unsigned int vectored; unsigned int write_zeroes_on_trim; enum fio_blkio_wait_mode wait_mode; + unsigned int force_enable_completion_eventfd; }; static struct fio_option options[] = { @@ -132,6 +133,16 @@ static struct fio_option options[] = { .category = FIO_OPT_C_ENGINE, .group = FIO_OPT_G_LIBBLKIO, }, + { + .name = "libblkio_force_enable_completion_eventfd", + .lname = "Force enable the completion eventfd, even if unused", + .type = FIO_OPT_STR_SET, + .off1 = offsetof(struct fio_blkio_options, + force_enable_completion_eventfd), + .help = "This can impact performance", + .category = FIO_OPT_C_ENGINE, + .group = FIO_OPT_G_LIBBLKIO, + }, { .name = NULL, }, @@ -276,6 +287,11 @@ static int fio_blkio_setup(struct thread_data *td) return 1; } + if (options->hipri && options->force_enable_completion_eventfd) { + log_err("fio: option hipri is incompatible with option libblkio_force_enable_completion_eventfd\n"); + return 1; + } + if (fio_blkio_create_and_connect(td, &b) != 0) return 1; @@ -342,7 +358,8 @@ 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) { + if (options->wait_mode == FIO_BLKIO_WAIT_MODE_EVENTFD || + options->force_enable_completion_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); diff --git a/fio.1 b/fio.1 index 1a810214..da548303 100644 --- a/fio.1 +++ b/fio.1 @@ -2633,7 +2633,8 @@ 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. This is incompatible with \fBlibblkio_wait_mode=eventfd\fR. +Use poll queues. This is incompatible with \fBlibblkio_wait_mode=eventfd\fR and +\fBlibblkio_force_enable_completion_eventfd\fR. .TP .BI (libblkio)libblkio_vectored Submit vectored read and write requests. @@ -2654,6 +2655,13 @@ 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. +.RE +.RE +.TP +.BI (libblkio)libblkio_force_enable_completion_eventfd +Enable the queue's completion eventfd even when unused. This may impact +performance. The default is to enable it only if +\fBlibblkio_wait_mode=eventfd\fR. .SS "I/O depth" .TP .BI iodepth \fR=\fPint -- 2.25.1