diff options
| -rw-r--r-- | storage/innobase/include/os0file.h | 2 | ||||
| -rw-r--r-- | tpool/aio_linux.cc | 29 |
2 files changed, 21 insertions, 10 deletions
diff --git a/storage/innobase/include/os0file.h b/storage/innobase/include/os0file.h index 760a68551f5..149da54b63c 100644 --- a/storage/innobase/include/os0file.h +++ b/storage/innobase/include/os0file.h @@ -264,7 +264,7 @@ struct os_file_size_t { os_offset_t m_alloc_size; }; -static const ulint OS_AIO_N_PENDING_IOS_PER_THREAD = 256; +constexpr ulint OS_AIO_N_PENDING_IOS_PER_THREAD= 256; extern ulint os_n_file_reads; extern ulint os_n_file_writes; diff --git a/tpool/aio_linux.cc b/tpool/aio_linux.cc index c335c54964d..91d1d08c3ff 100644 --- a/tpool/aio_linux.cc +++ b/tpool/aio_linux.cc @@ -22,13 +22,22 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02111 - 1301 USA*/ # include <libaio.h> # include <sys/syscall.h> -/* - A hack, which so far seems to allow allow getevents thread to be interrupted - by io_destroy() from another thread - - libaio's io_getevent() would sometimes crash when attempting this feat, - thus the raw syscall. - +/** + Invoke the io_getevents() system call. + + @param ctx context from io_setup() + @param min_nr minimum number of completion events to wait for + @param nr maximum number of completion events to collect + @param ev the collected events + + In https://pagure.io/libaio/c/7cede5af5adf01ad26155061cc476aad0804d3fc + the io_getevents() implementation in libaio was "optimized" so that it + would elide the system call when there are no outstanding requests + and a timeout was specified. + + The libaio code for dereferencing ctx would occasionally trigger + SIGSEGV if io_destroy() was concurrently invoked from another thread. + Hence, we use the raw system call. */ static int my_getevents(io_context_t ctx, long min_nr, long nr, io_event *ev) { @@ -59,8 +68,6 @@ namespace tpool { #ifdef LINUX_NATIVE_AIO -#define MAX_EVENTS 256 - class aio_linux final : public aio { thread_pool *m_pool; @@ -70,6 +77,10 @@ class aio_linux final : public aio static void getevent_thread_routine(aio_linux *aio) { + /* We collect this many events at a time. os_aio_init() would + multiply OS_AIO_N_PENDING_THREADS by the number of read and write threads + and ultimately pass it to io_setup() via thread_pool::configure_aio(). */ + constexpr unsigned MAX_EVENTS= 256; io_event events[MAX_EVENTS]; for (;;) { |