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Re: [Qemu-devel] [PATCH 01/15] coroutine-ucontext: mmap stack memory
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 01/15] coroutine-ucontext: mmap stack memory |
Date: |
Tue, 28 Jun 2016 13:04:13 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 |
On 28/06/2016 11:01, Peter Lieven wrote:
> +#ifdef MAP_GROWSDOWN
> + co->stack = mmap(NULL, COROUTINE_STACK_SIZE, PROT_READ | PROT_WRITE,
> + MAP_PRIVATE | MAP_ANONYMOUS | MAP_GROWSDOWN, -1, 0);
> + if (co->stack == MAP_FAILED) {
> + abort();
> + }
> + /* add a guard page at bottom of the stack */
> + if (mmap(co->stack, getpagesize(), PROT_NONE,
> + MAP_PRIVATE | MAP_ANONYMOUS | MAP_GROWSDOWN, -1, 0) == MAP_FAILED) {
> + abort();
> + }
Nevermind, you added a guard page! Good! :) And actually it looks like
the stack usage has been mostly tamed, at least for the block layer.
On the other hand MAP_GROWSDOWN automatically adds a guard page since
Linux 3.9 (see commit 09884964335e, "mm: do not grow the stack vma just
because of an overrun on preceding vma", 2013-02-27), so as it turns out
you don't even need the guard page!
Paolo
> +#else
> co->stack = g_malloc(stack_size);
> +#endif
- [Qemu-devel] [PATCH 00/15] optimize Qemu RSS usage, Peter Lieven, 2016/06/28
- [Qemu-devel] [PATCH 01/15] coroutine-ucontext: mmap stack memory, Peter Lieven, 2016/06/28
- [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Peter Lieven, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Paolo Bonzini, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Dr. David Alan Gilbert, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Peter Lieven, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Dr. David Alan Gilbert, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Peter Lieven, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Dr. David Alan Gilbert, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Peter Lieven, 2016/06/30
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Peter Lieven, 2016/06/28
- Re: [Qemu-devel] [PATCH 03/15] coroutine-ucontext: reduce stack size to 64kB, Paolo Bonzini, 2016/06/28