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Re: [Qemu-devel] [PATCH v3 13/34] tcg: Add atomic helpers
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH v3 13/34] tcg: Add atomic helpers |
Date: |
Tue, 13 Sep 2016 11:00:11 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 |
On 09/12/2016 06:47 AM, Alex Bennée wrote:
>> > + /* Notice an IO access, or a notdirty page. */
>> > + if (unlikely(tlb_addr & ~TARGET_PAGE_MASK)) {
>> > + /* There's really nothing that can be done to
>> > + support this apart from stop-the-world. */
>> > + goto stop_the_world;
> We are also triggering on TLB_NOTDIRTY here in the case where a
> conditional write is the first write to a page. I don't know if a
> stop_the_world is required at this point but we will need to ensure we
> clear bits as notdirty_mem_write() does.
>
You're quite right that we could probably special-case TLB_NOTDIRTY here such
that (1) we needn't leave the cpu loop, and (2) needn't utilize the actual
"write" part of notdirty_mem_write; just set the bits then fall through to the
actual atomic instruction below.
r~
- [Qemu-devel] [PATCH v3 18/34] target-i386: emulate LOCK'ed INC using atomic helper, (continued)
Re: [Qemu-devel] [PATCH v3 13/34] tcg: Add atomic helpers, Alex Bennée, 2016/09/12
- Re: [Qemu-devel] [PATCH v3 13/34] tcg: Add atomic helpers,
Richard Henderson <=
Re: [Qemu-devel] [PATCH v3 13/34] tcg: Add atomic helpers, Alex Bennée, 2016/09/13
[Qemu-devel] [PATCH v3 19/34] target-i386: emulate LOCK'ed NOT using atomic helper, Richard Henderson, 2016/09/03
[Qemu-devel] [PATCH v3 15/34] tcg: Add CONFIG_ATOMIC64, Richard Henderson, 2016/09/03
[Qemu-devel] [PATCH v3 24/34] target-i386: remove helper_lock(), Richard Henderson, 2016/09/03
[Qemu-devel] [PATCH v3 21/34] target-i386: emulate LOCK'ed XADD using atomic helper, Richard Henderson, 2016/09/03
[Qemu-devel] [PATCH v3 25/34] tests: add atomic_add-bench, Richard Henderson, 2016/09/03