[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH] block: Let bdrv_drain_all() to call aio_poll()
From: |
Alexander Yarygin |
Subject: |
Re: [Qemu-devel] [PATCH] block: Let bdrv_drain_all() to call aio_poll() for each AioContext |
Date: |
Thu, 14 May 2015 17:29:21 +0300 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
Paolo Bonzini <address@hidden> writes:
> On 13/05/2015 18:34, Alexander Yarygin wrote:
>> Ah, right. We need second loop, something like this:
>>
>> @@ -2030,20 +2033,33 @@ void bdrv_drain(BlockDriverState *bs)
>> void bdrv_drain_all(void)
>> {
>> /* Always run first iteration so any pending completion BHs run */
>> - bool busy = true;
>> + bool busy = true, pending = false;
>> BlockDriverState *bs;
>> + GList *aio_ctxs = NULL, *ctx;
>> + AioContext *aio_context;
>>
>> while (busy) {
>> busy = false;
>>
>> QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
>> - AioContext *aio_context = bdrv_get_aio_context(bs);
>> + aio_context = bdrv_get_aio_context(bs);
>>
>> aio_context_acquire(aio_context);
>> busy |= bdrv_drain_one(bs);
>> aio_context_release(aio_context);
>> + if (!aio_ctxs || !g_list_find(aio_ctxs, aio_context))
>> + aio_ctxs = g_list_append(aio_ctxs, aio_context);
>> + }
>> + pending = busy;
>> +
>> + for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
>> + aio_context = ctx->data;
>> + aio_context_acquire(aio_context);
>> + busy |= aio_poll(aio_context, pending);
>> + aio_context_release(aio_context);
>> }
>> }
>> + g_list_free(aio_ctxs);
>> }
>>
>> That looks quite ugly for me and breaks consistence of bdrv_drain_one()
>> since it doesn't call aio_poll() anymore...
>
> It's not ugly. After your patch bdrv_drain_one doesn't call aio_poll,
> while bdrv_drain and bdrv_drain_all call bdrv_drain_one + aio_poll. All
> callers of bdrv_drain_one are consistent.
>
> Perhaps you can rename bdrv_drain_one to bdrv_flush_io_queue (inlining
> the existing bdrv_flush_io_queue into it)? That would work very well
> for me.
>
> Paolo
Hmm, bdrv_flush_io_queue() is public, but has no users. How about
different name, maybe something like "bdrv_drain_requests_one" or so?
Otherwise here is a patch related to renaming to bdrv_flush_io_queue()
below. If it's ok, I will respin the whole patch.
Thanks.
--- a/block.c
+++ b/block.c
@@ -1987,11 +1987,17 @@ static bool bdrv_requests_pending(BlockDriverState *bs)
return false;
}
-static bool bdrv_drain_one(BlockDriverState *bs)
+static bool bdrv_flush_io_queue(BlockDriverState *bs)
{
bool bs_busy;
+ BlockDriver *drv = bs->drv;
+
+ if (drv && drv->bdrv_flush_io_queue) {
+ drv->bdrv_flush_io_queue(bs);
+ } else if (bs->file) {
+ bdrv_flush_io_queue(bs->file);
+ }
- bdrv_flush_io_queue(bs);
bdrv_start_throttled_reqs(bs);
bs_busy = bdrv_requests_pending(bs);
return bs_busy;
@@ -2013,7 +2019,7 @@ void bdrv_drain(BlockDriverState *bs)
while (busy) {
/* Keep iterating */
- busy = bdrv_drain_one(bs);
+ busy = bdrv_flush_io_queue(bs);
busy |= aio_poll(bdrv_get_aio_context(bs), busy);
}
}
@@ -2044,7 +2050,7 @@ void bdrv_drain_all(void)
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
- busy |= bdrv_drain_one(bs);
+ busy |= bdrv_flush_io_queue(bs);
if (!aio_ctxs || !g_slist_find(aio_ctxs, aio_context)) {
busy |= aio_poll(aio_context, busy);
aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
@@ -6088,16 +6094,6 @@ void bdrv_io_unplug(BlockDriverState *bs)
}
}
-void bdrv_flush_io_queue(BlockDriverState *bs)
-{
- BlockDriver *drv = bs->drv;
- if (drv && drv->bdrv_flush_io_queue) {
- drv->bdrv_flush_io_queue(bs);
- } else if (bs->file) {
- bdrv_flush_io_queue(bs->file);
- }
-}
-
static bool append_open_options(QDict *d, BlockDriverState *bs)
{
const QDictEntry *entry;
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -565,7 +565,6 @@ int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry
*geo);
void bdrv_io_plug(BlockDriverState *bs);
void bdrv_io_unplug(BlockDriverState *bs);
-void bdrv_flush_io_queue(BlockDriverState *bs);
BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
Re: [Qemu-devel] [Qemu-block] [PATCH] block: Let bdrv_drain_all() to call aio_poll() for each AioContext, Alberto Garcia, 2015/05/13