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

From: Greg Kroah-Hartman
Date: Wed Jun 12 2024 - 05:59:05 EST


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@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