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

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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?

> ----------------------------------------------------------------
> 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@vivo.com>
> ---
>  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