Date: Thu, 20 Mar 2008 11:15:24 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: Roman Divacky <rdivacky@FreeBSD.org> Cc: freebsd-emulation@FreeBSD.org Subject: Re: [PATCH]: additional futex operations Message-ID: <20080320111524.0j8stbuny84gwswc@webmail.leidinger.net> In-Reply-To: <20080320085122.GB32936@freebsd.org> References: <96317980@ipt.ru> <20080319204521.GA98846@freebsd.org> <20080320080703.ws5h2vaqskkw4w0s@webmail.leidinger.net> <20080320085122.GB32936@freebsd.org>
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Quoting Roman Divacky <rdivacky@FreeBSD.org> (from Thu, 20 Mar 2008 =20
09:51:22 +0100):
> On Thu, Mar 20, 2008 at 08:07:03AM +0100, Alexander Leidinger wrote:
>> Quoting Roman Divacky <rdivacky@FreeBSD.org> (from Wed, 19 Mar 2008
>> 21:45:21 +0100):
>>
>> >
>> >can you guys please test:
>> >
>> >=09www.vlakno.cz/~rdivacky/futex_private_pi.patch
>> >
>> >especially if linux-firefox is still broken with this patch.
>>
>> What do you think about rate limiting (only one) the FD case instead
>> of hiding it completely (and using the content of the comment as the
>> message to print with a little bit of "only report if something is
>> obviously broken")? This way we could determine if we need it for
>> linux-backwards compatibility.
>
> I dont think the FD case is used widely and we correctly (now) return
> ENOSYS so no problems should be here.
The thought behind this is, that we can go from "should be" to "are". =20
Doing a rate limited logging (print the message once) in -current (not =20
in a MFC) should be enough to get a better idea.
> Also.. if anyone is willing/able to implement the FD backing I think such
> person is skilled enough to see what is the problem even without the print=
f.
It's not about finding some to implement it, it's about getting _hard_ =20
facts in our userbase.
> It can only confuse normal people I think..
For this reason I said to change the comment. Here's what I mean:
---snip---
static int limit_once =3D 0;
if (!limit_once) {
limit_once =3D 1;
printf("FD futex not implemented, linux wants to deprecate =20
it. Do not report this, except when you see a real failure/misbehavior =20
because of this.");
}
return (ENOSYS);
---snip---
> I'd let it be as it is
>
>> Is this a proof of concept (do you plan to make a no-op
>> LINUX_FUTEX_PRIVATE_FLAG case in the switch to be consistent) or the
>> final solution? I see pros/cons for both and I think it doesn't matter
>> how it is done, I'm just curious about your opinion.
>
> we DO implement private futexes. we DONT implement shared ones. We dont
> share futexes on "vm" structure or file descriptor. The only reason why
> it works is because 99% of application want private futexes but dont
> claim so :)
Yes, I understand that. What I wanted to know is, if you want to add a =20
if/case statement with LINUX_FUTEX_PRIVATE_FLAG which does nothing =20
(except containing the comment) for consistency/strict correctness =20
reasons. As told above, I see value in both ways of doing it. I assume =20
now you want to commit the patch as is, no need to comment further on =20
this.
Bye,
Alexander.
--=20
You know you have a small apartment when Rice Krispies echo.
=09=09-- S. Rickly Christian
http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID =3D B0063FE7
http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID =3D 72077137
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