Re: [Qemu-devel] [PATCH] AIO: Reduce number of threads for 32bit hosts

[Stefan Hajnoczi]

On Wed, Jan 14, 2015 at 01:56:56AM +0100, Alexander Graf wrote:
> On hosts with limited virtual address space (32bit pointers), we can very
> easily run out of virtual memory with big thread pools.
> 
> Instead, we should limit ourselves to small pools to keep memory footprint
> low on those systems.
> 
> This patch fixes random VM stalls like
> 
>   (process:25114): GLib-ERROR **: gmem.c:103: failed to allocate 1048576 bytes
> 
> on 32bit ARM systems for me.
> 
> Signed-off-by: Alexander Graf <address@hidden>
> ---
>  thread-pool.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/thread-pool.c b/thread-pool.c
> index e2cac8e..87a3ea9 100644
> --- a/thread-pool.c
> +++ b/thread-pool.c
> @@ -299,7 +299,12 @@ static void thread_pool_init_one(ThreadPool *pool, 
> AioContext *ctx)
>      qemu_mutex_init(&pool->lock);
>      qemu_cond_init(&pool->worker_stopped);
>      qemu_sem_init(&pool->sem, 0);
> -    pool->max_threads = 64;
> +    if (sizeof(pool) == 4) {
> +        /* 32bit systems run out of virtual memory quickly */
> +        pool->max_threads = 4;
> +    } else {
> +        pool->max_threads = 64;
> +    }
>      pool->new_thread_bh = aio_bh_new(ctx, spawn_thread_bh_fn, pool);
>  
>      QLIST_INIT(&pool->head);

This patch has not been applied.

Have there been any changes in this area?

Stefan

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