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Re: [PATCH 5/6] block/block-copy: add memory limit
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
Re: [PATCH 5/6] block/block-copy: add memory limit |
Date: |
Mon, 7 Oct 2019 17:10:37 +0000 |
07.10.2019 18:27, Max Reitz wrote:
> On 03.10.19 19:15, Vladimir Sementsov-Ogievskiy wrote:
>> Currently total allocation for parallel requests to block-copy instance
>> is unlimited. Let's limit it to 128 MiB.
>>
>> For now block-copy is used only in backup, so actually we limit total
>> allocation for backup job.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>> ---
>> include/block/block-copy.h | 3 +++
>> block/block-copy.c | 5 +++++
>> 2 files changed, 8 insertions(+)
>>
>> diff --git a/include/block/block-copy.h b/include/block/block-copy.h
>> index e2e135ff1b..bb666e7068 100644
>> --- a/include/block/block-copy.h
>> +++ b/include/block/block-copy.h
>> @@ -16,6 +16,7 @@
>> #define BLOCK_COPY_H
>>
>> #include "block/block.h"
>> +#include "qemu/co-shared-amount.h"
>>
>> typedef struct BlockCopyInFlightReq {
>> int64_t start_byte;
>> @@ -69,6 +70,8 @@ typedef struct BlockCopyState {
>> */
>> ProgressResetCallbackFunc progress_reset_callback;
>> void *progress_opaque;
>> +
>> + QemuCoSharedAmount *mem;
>> } BlockCopyState;
>>
>> BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
>> diff --git a/block/block-copy.c b/block/block-copy.c
>> index cc49d2345d..e700c20d0f 100644
>> --- a/block/block-copy.c
>> +++ b/block/block-copy.c
>> @@ -21,6 +21,7 @@
>> #include "qemu/units.h"
>>
>> #define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
>> +#define BLOCK_COPY_MAX_MEM (128 * MiB)
>>
>> static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,
>> int64_t start,
>> @@ -64,6 +65,7 @@ void block_copy_state_free(BlockCopyState *s)
>> }
>>
>> bdrv_release_dirty_bitmap(s->source->bs, s->copy_bitmap);
>> + qemu_co_shared_amount_free(s->mem);
>> g_free(s);
>> }
>>
>> @@ -95,6 +97,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source,
>> BdrvChild *target,
>> .cluster_size = cluster_size,
>> .len = bdrv_dirty_bitmap_size(copy_bitmap),
>> .write_flags = write_flags,
>> + .mem = qemu_co_shared_amount_new(BLOCK_COPY_MAX_MEM),
>> };
>>
>> s->copy_range_size = QEMU_ALIGN_DOWN(max_transfer, cluster_size),
>> @@ -316,7 +319,9 @@ int coroutine_fn block_copy(BlockCopyState *s,
>>
>> bdrv_reset_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
>>
>> + qemu_co_get_amount(s->mem, chunk_end - start);
>
> Now that I see it like this, maybe the name is too short. This sounds
> like it was trying to get some amount of coroutines.
>
> Would “qemu_co_get_from_shared_amount” be too long? (Something like
> qemu_co_sham_alloc() would be funny, but maybe not. :-) Or maybe
> exactly because it”s funny.)
>
hmm sham may be interpreted as shared memory, not only like shame..
And if we call it _alloc, the opposite should be _free, but how to
distinguish it from freeing the whole object? Hmm, use create/destroy for
the whole object maybe.
May be, drop "qemu_" ? It's not very informative. Or may be drop "co_"?.
I don't like shaming my shared amount :)
May be, we should imagine, what are we allocating? May be balls?
struct BallAllocator
ball_allocator_create
ball_allocator_destroy
co_try_alloc_balls
co_alloc_balls
co_free_balls
Or bars? Or which thing may be used for funny naming and to not intersect
with existing concepts like memory?
>
>> ret = block_copy_do_copy(s, start, chunk_end, error_is_read);
>> + qemu_co_put_amount(s->mem, chunk_end - start);
>> if (ret < 0) {
>> bdrv_set_dirty_bitmap(s->copy_bitmap, start, chunk_end -
>> start);
>> break;
>>
>
>
--
Best regards,
Vladimir
[PATCH 4/6] util: introduce co-shared-amount, Vladimir Sementsov-Ogievskiy, 2019/10/03
[PATCH 1/6] block/block-copy: allocate buffer in block_copy_with_bounce_buffer, Vladimir Sementsov-Ogievskiy, 2019/10/03