Re: [PATCH] binder_alloc: replace kcalloc with kvcalloc to mitigate OOM issues

[Lei Liu]

On 2024/6/12 17:58, Greg Kroah-Hartman wrote:
> On Tue, Jun 11, 2024 at 04:56:28PM +0800, Lei Liu wrote:
>
> > In binder_alloc, there is a frequent need for order3 memory 
> > allocation, especially on small-memory mobile devices, which can lead 
> > to OOM and cause foreground applications to be killed, resulting in 
> > flashbacks. We use kvcalloc to allocate memory, which can reduce 
> > system OOM occurrences, as well as decrease the time and probability 
> > of failure for order3 memory allocations. Additionally, it can also 
> > improve the throughput of binder (as verified by Google's 
> > binder_benchmark testing tool). We have conducted multiple tests on 
> > an 8GB memory phone, and the performance of kvcalloc is better. Below 
> > is a partial excerpt of the test data. throughput = (size * 
> > Iterations)/Time Benchmark-kvcalloc Time CPU Iterations 
> > throughput(Gb/s) 
> > ---------------------------------------------------------------- 
> > BM_sendVec_binder-4096 30926 ns 20481 ns 34457 4563.66↑ 
> > BM_sendVec_binder-8192 42667 ns 30837 ns 22631 4345.11↑ 
> > BM_sendVec_binder-16384 67586 ns 52381 ns 13318 3228.51↑ 
> > BM_sendVec_binder-32768 116496 ns 94893 ns 7416 2085.97↑ 
> > BM_sendVec_binder-65536 265482 ns 209214 ns 3530 871.40↑ 
> > Benchmark-kvcalloc Time CPU Iterations throughput(Gb/s) 
> Both benchmarks are the same? Or is this labeled incorrectly?
I'm really sorry, I got the title of the table wrong, here are the 
updated data:
throughput = (size * Iterations)/Time
kvcalloc->kvmalloc:
Benchmark-kvcalloc    Time    CPU    Iterations    throughput(Gb/s)
----------------------------------------------------------------
BM_sendVec_binder-4096    30926 ns    20481 ns    34457    4563.66↑
BM_sendVec_binder-8192    42667 ns    30837 ns    22631    4345.11↑
BM_sendVec_binder-16384    67586 ns    52381 ns    13318    3228.51↑
BM_sendVec_binder-32768    116496 ns    94893 ns    7416    2085.97↑
BM_sendVec_binder-65536    265482 ns    209214 ns    3530    871.40↑

kcalloc->kmalloc
Benchmark-kcalloc    Time    CPU    Iterations    throughput(Gb/s)
----------------------------------------------------------------
BM_sendVec_binder-4096    39070 ns    24207 ns    31063    3256.56
BM_sendVec_binder-8192    49476 ns    35099 ns    18817    3115.62
BM_sendVec_binder-16384    76866 ns    58924 ns    11883    2532.86
BM_sendVec_binder-32768    134022 ns    102788 ns    6535    1597.78
BM_sendVec_binder-65536    281004 ns    220028 ns    3135    731.14
> > ---------------------------------------------------------------- 
> > BM_sendVec_binder-4096 39070 ns 24207 ns 31063 3256.56 
> > BM_sendVec_binder-8192 49476 ns 35099 ns 18817 3115.62 
> > BM_sendVec_binder-16384 76866 ns 58924 ns 11883 2532.86 
> > BM_sendVec_binder-32768 134022 ns 102788 ns 6535 1597.78 
> > BM_sendVec_binder-65536 281004 ns 220028 ns 3135 731.14 
> > Signed-off-by: Lei Liu <liulei.rjpt@xxxxxxxx> --- 
> > drivers/android/binder_alloc.c | 6 +++--- 1 file changed, 3 
> > insertions(+), 3 deletions(-) diff --git 
> > a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c 
> > index 2e1f261ec5c8..5dcab4a5e341 100644 --- 
> > a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c 
> > @@ -836,7 +836,7 @@ int binder_alloc_mmap_handler(struct binder_alloc 
> > *alloc, alloc->buffer = vma->vm_start; - alloc->pages = 
> > kcalloc(alloc->buffer_size / PAGE_SIZE, + alloc->pages = 
> > kvcalloc(alloc->buffer_size / PAGE_SIZE, sizeof(alloc->pages[0]), 
> > GFP_KERNEL); 
> Nit, update the indentation please. 
> thanks, greg k-h
The previous incorrect table title has been updated. Please help review 
it again.

Thank you!
Lei Liu