diff options
Diffstat (limited to 'util/aio-posix.c')
| -rw-r--r-- | util/aio-posix.c | 114 |
1 files changed, 72 insertions, 42 deletions
diff --git a/util/aio-posix.c b/util/aio-posix.c index 06bf9f456c..2e0a5dadc4 100644 --- a/util/aio-posix.c +++ b/util/aio-posix.c @@ -28,6 +28,9 @@ /* Stop userspace polling on a handler if it isn't active for some time */ #define POLL_IDLE_INTERVAL_NS (7 * NANOSECONDS_PER_SECOND) +static void adjust_polling_time(AioContext *ctx, AioPolledEvent *poll, + int64_t block_ns); + bool aio_poll_disabled(AioContext *ctx) { return qatomic_read(&ctx->poll_disable_cnt); @@ -392,7 +395,8 @@ static bool aio_dispatch_handler(AioContext *ctx, AioHandler *node) * scanning all handlers with aio_dispatch_handlers(). */ static bool aio_dispatch_ready_handlers(AioContext *ctx, - AioHandlerList *ready_list) + AioHandlerList *ready_list, + int64_t block_ns) { bool progress = false; AioHandler *node; @@ -400,6 +404,14 @@ static bool aio_dispatch_ready_handlers(AioContext *ctx, while ((node = QLIST_FIRST(ready_list))) { QLIST_REMOVE(node, node_ready); progress = aio_dispatch_handler(ctx, node) || progress; + + /* + * Adjust polling time only after aio_dispatch_handler(), which can + * add the handler to ctx->poll_aio_handlers. + */ + if (ctx->poll_max_ns && QLIST_IS_INSERTED(node, node_poll)) { + adjust_polling_time(ctx, &node->poll, block_ns); + } } return progress; @@ -579,13 +591,19 @@ static bool run_poll_handlers(AioContext *ctx, AioHandlerList *ready_list, static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list, int64_t *timeout) { + AioHandler *node; int64_t max_ns; if (QLIST_EMPTY_RCU(&ctx->poll_aio_handlers)) { return false; } - max_ns = qemu_soonest_timeout(*timeout, ctx->poll_ns); + max_ns = 0; + QLIST_FOREACH(node, &ctx->poll_aio_handlers, node_poll) { + max_ns = MAX(max_ns, node->poll.ns); + } + max_ns = qemu_soonest_timeout(*timeout, max_ns); + if (max_ns && !ctx->fdmon_ops->need_wait(ctx)) { /* * Enable poll mode. It pairs with the poll_set_started() in @@ -600,6 +618,46 @@ static bool try_poll_mode(AioContext *ctx, AioHandlerList *ready_list, return false; } +static void adjust_polling_time(AioContext *ctx, AioPolledEvent *poll, + int64_t block_ns) +{ + if (block_ns <= poll->ns) { + /* This is the sweet spot, no adjustment needed */ + } else if (block_ns > ctx->poll_max_ns) { + /* We'd have to poll for too long, poll less */ + int64_t old = poll->ns; + + if (ctx->poll_shrink) { + poll->ns /= ctx->poll_shrink; + } else { + poll->ns = 0; + } + + trace_poll_shrink(ctx, old, poll->ns); + } else if (poll->ns < ctx->poll_max_ns && + block_ns < ctx->poll_max_ns) { + /* There is room to grow, poll longer */ + int64_t old = poll->ns; + int64_t grow = ctx->poll_grow; + + if (grow == 0) { + grow = 2; + } + + if (poll->ns) { + poll->ns *= grow; + } else { + poll->ns = 4000; /* start polling at 4 microseconds */ + } + + if (poll->ns > ctx->poll_max_ns) { + poll->ns = ctx->poll_max_ns; + } + + trace_poll_grow(ctx, old, poll->ns); + } +} + bool aio_poll(AioContext *ctx, bool blocking) { AioHandlerList ready_list = QLIST_HEAD_INITIALIZER(ready_list); @@ -607,6 +665,7 @@ bool aio_poll(AioContext *ctx, bool blocking) bool use_notify_me; int64_t timeout; int64_t start = 0; + int64_t block_ns = 0; /* * There cannot be two concurrent aio_poll calls for the same AioContext (or @@ -679,49 +738,13 @@ bool aio_poll(AioContext *ctx, bool blocking) aio_notify_accept(ctx); - /* Adjust polling time */ + /* Calculate blocked time for adaptive polling */ if (ctx->poll_max_ns) { - int64_t block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start; - - if (block_ns <= ctx->poll_ns) { - /* This is the sweet spot, no adjustment needed */ - } else if (block_ns > ctx->poll_max_ns) { - /* We'd have to poll for too long, poll less */ - int64_t old = ctx->poll_ns; - - if (ctx->poll_shrink) { - ctx->poll_ns /= ctx->poll_shrink; - } else { - ctx->poll_ns = 0; - } - - trace_poll_shrink(ctx, old, ctx->poll_ns); - } else if (ctx->poll_ns < ctx->poll_max_ns && - block_ns < ctx->poll_max_ns) { - /* There is room to grow, poll longer */ - int64_t old = ctx->poll_ns; - int64_t grow = ctx->poll_grow; - - if (grow == 0) { - grow = 2; - } - - if (ctx->poll_ns) { - ctx->poll_ns *= grow; - } else { - ctx->poll_ns = 4000; /* start polling at 4 microseconds */ - } - - if (ctx->poll_ns > ctx->poll_max_ns) { - ctx->poll_ns = ctx->poll_max_ns; - } - - trace_poll_grow(ctx, old, ctx->poll_ns); - } + block_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - start; } progress |= aio_bh_poll(ctx); - progress |= aio_dispatch_ready_handlers(ctx, &ready_list); + progress |= aio_dispatch_ready_handlers(ctx, &ready_list, block_ns); aio_free_deleted_handlers(ctx); @@ -767,11 +790,18 @@ void aio_context_use_g_source(AioContext *ctx) void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns, int64_t grow, int64_t shrink, Error **errp) { + AioHandler *node; + + qemu_lockcnt_inc(&ctx->list_lock); + QLIST_FOREACH(node, &ctx->aio_handlers, node) { + node->poll.ns = 0; + } + qemu_lockcnt_dec(&ctx->list_lock); + /* No thread synchronization here, it doesn't matter if an incorrect value * is used once. */ ctx->poll_max_ns = max_ns; - ctx->poll_ns = 0; ctx->poll_grow = grow; ctx->poll_shrink = shrink; |