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aio-posix: Factor out adjust_polling_time()

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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250307221634.71951-5-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2025-03-07 23:16:33 +01:00
parent 518db1013c
commit cf2e226fc6
1 changed files with 41 additions and 36 deletions
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77
util/aio-posix.c
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@ -600,6 +600,46 @@ 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);
@ -682,42 +722,7 @@ bool aio_poll(AioContext *ctx, bool blocking)
/* Adjust polling time */
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);
}
adjust_polling_time(ctx, &ctx->poll, block_ns);
}
progress |= aio_bh_poll(ctx);