在 2022/7/29 22:14, Richard Henderson 写道:
On 7/29/22 06:31, Peter Maydell wrote:
On Wed, 20 Jul 2022 at 12:30, Dr. David Alan Gilbert (git)
<dgilb...@redhat.com> wrote:
From: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
Setup a negative feedback system when vCPU thread
handling KVM_EXIT_DIRTY_RING_FULL exit by introducing
throttle_us_per_full field in struct CPUState. Sleep
throttle_us_per_full microseconds to throttle vCPU
if dirtylimit is in service.
Signed-off-by: Hyman Huang(黄勇) <huang...@chinatelecom.cn>
Reviewed-by: Peter Xu <pet...@redhat.com>
Message-Id:
<977e808e03a1cef5151cae75984658b6821be618.1656177590.git.huang...@chinatelecom.cn>
Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Hi; Coverity points out a problem with this code (CID 1490787):
Thanks for pointing out this bug. I'm making a access request for
https://scan.coverity.com so that coverity problem can be found once new
series be posted. Hoping this bug doesn't appear anymore. :)
+static inline int64_t dirtylimit_dirty_ring_full_time(uint64_t
dirtyrate)
+{
+ static uint64_t max_dirtyrate;
+ uint32_t dirty_ring_size = kvm_dirty_ring_size();
+ uint64_t dirty_ring_size_meory_MB =
+ dirty_ring_size * TARGET_PAGE_SIZE >> 20;
Because dirty_ring_size and TARGET_PAGE_SIZE are both 32 bits,
this multiplication will be done as a 32-bit operation,
which could overflow. You should cast one of the operands
to uint64_t to ensure that the operation is done as a 64 bit
multiplication.
To compute MB, you don't need multiplication:
dirty_ring_size >> (20 - TARGET_PAGE_BITS)
In addition, why the mismatch in type? dirty_ring_size_memory_MB can
never be larger than dirty_ring_size.
r~
I'll post bugfix patch later as your suggestion, please review, thanks.
Side note: typo in the variable name: should be 'memory'.
+ if (max_dirtyrate < dirtyrate) {
+ max_dirtyrate = dirtyrate;
+ }
+
+ return dirty_ring_size_meory_MB * 1000000 / max_dirtyrate;
+}
thanks
-- PMM
