- From: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
- Date: Tue, 30 Jul 2013 21:16:36 +0300
- To: Joseph Berkovitz <joe@noteflight.com>
- Cc: Jer Noble <jer.noble@apple.com>, Ehsan Akhgari <ehsan.akhgari@gmail.com>, "Robert O'Callahan" <robert@ocallahan.org>, Olivier Thereaux <Olivier.Thereaux@bbc.co.uk>, WG <public-audio@w3.org>
- Message-ID: <CAJhzemU5Zntd7P6dnedxBGm9hqCSHFEEohCSDi2Gnwuwd-oOSw@mail.gmail.com>
On Tue, Jul 30, 2013 at 8:00 PM, Joseph Berkovitz <joe@noteflight.com>wrote: > Just to clarify (because this discussion has been so lengthy), my > understanding is this performance cost (whatever its size) is associated > with *fixing* the current shared-memory model to avoid the security > problems resulting from visibility of shared memory that > is no-longer-owned due to neutering. It is not a side-effect of anything to > do with Jer's proposed new API change. Correct? > IIUC, yes, and to clarify, I was making a point that we're going to impose a performance penalty somewhere with all proposals, including by speccing whatever Webkit/Blink are doing right now, so I was not arguing against Jer's proposal to fix the problem on our side, quite the contrary. :) Cheers, Jussi > The original non-neuterableness proposal from Chris Rogers appears to have > occurred off-list AFAICT and all I find are responses to that proposal. > > Sorry to be asking these questions but I've been studying the mail > archives assiduously and want to make sure I am making an informed vote and > participating in the discussion in an informed way. It is rather a > challenge to stay on top of these issues. I appreciate everyone's help. > > …Joe > > > On Jul 30, 2013, at 12:05 PM, Jussi Kalliokoski < > jussi.kalliokoski@gmail.com> wrote: > > On Tue, Jul 30, 2013 at 6:52 PM, Jer Noble <jer.noble@apple.com> wrote: > >> >> On Jul 30, 2013, at 8:47 AM, Jussi Kalliokoski < >> jussi.kalliokoski@gmail.com> wrote: >> >> Does this impose a performance cost on Float32Array access, BTW? I tried >> figuring it out on my own but I've been following leads in the WebKit >> source for a while and haven't found the code that does this. >> >> >> We re-used the high-order bit in ArrayBufferView's offset to track >> non-neuterableness. So yes, in that offset calculations now need to mask >> off that bit, but the cost is negligable. >> >> See: >> http://trac.webkit.org/browser/trunk/Source/WTF/wtf/ArrayBufferView.h#L134 >> http://trac.webkit.org/browser/trunk/Source/WTF/wtf/ArrayBuffer.cpp#L36 >> > > Thanks! So, correct me if I'm wrong, but we're discussing imposing a > performance cost (arguably negligible) to Typed Arrays use to avoid > imposing a performance cost (arguably negligible) on the Web Audio API. To > be honest, (probably unsurprisingly) I'd rather we take risks like this in > our own API instead of on an API that's the foundation of high performance > JS. We can add more surface to our API to make it faster if need be, but if > we impose performance costs to the basic use of Typed Arrays, that's > irreversible and damages the whole platform. > > Cheers, > Jussi > > >> -Jer >> > > > >
Received on Tuesday, 30 July 2013 18:17:04 UTC