From: Hugh Dickins <hugh@veritas.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ulrich Drepper <drepper@redhat.com>,
Jamie Lokier <jamie@shareable.org>, Andrew Morton <akpm@osdl.org>,
Stephen Hemminger <shemminger@osdl.org>,
Linus Torvalds <torvalds@osdl.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Re: today's futex changes
Date: Mon, 8 Sep 2003 18:33:04 +0100 (BST) [thread overview]
Message-ID: <Pine.LNX.4.44.0309081746180.7008-100000@localhost.localdomain> (raw)
In-Reply-To: <20030908102309.0AC4E2C013@lists.samba.org>
On Mon, 8 Sep 2003, Rusty Russell wrote:
> OK, I've updated my patch on top of this. Mainly cosmetic, please
> review.
>
> Name: Minor Tweaks To Jamie Lokier's Futex Patch
> Author: Rusty Russell
> Status: Booted on 2.6.0-test4-bk9
> Depends: Misc/futex-hugh.patch.gz
>
> D: Minor changes to Jamie's excellent futex patch.
> D: 1) Remove obsolete comment above hash array decl.
> D: 2) Semantics of futex on read-only pages unclear: require write perm.
> D: 3) Clarify comment about TASK_INTERRUPTIBLE.
> D: 4) Andrew Morton says spurious wakeup is a bug. Catch it.
> D: 5) Use Jenkins hash.
Most of it (the futex_wait tweaks) looked fine to me -
though I look forward to the first report of that BUG().
Part 2, requiring VM_WRITE and removing the comment on VM_MAYSHARE,
seems a regression to me. Perhaps I misinterpreted Linus' action in
taking Jamie's patch: I took that to mean he relented a little on his
hardline position about VM_SHARED, and now accepts that in this context
VM_MAYSHARE is more appropriate (easier to document). I know I argued
that readonly futices are pointless, but I thought Jamie gave a good
picture of how a readonly view could still be used. I'd rather that
part were a separate patch, so Linus can merge or not as he wishes.
In part 5, the Jenkins hashing, I was puzzled by the "/4" in
+ (sizeof(key->both.word)+sizeof(key->both.ptr))/4,
both.ptr would be a multiple of 32 (? seems to be that way on PIII
and P4, though I gave up trying to work out quite how slab.c aligns),
and both.word would be a multiple of 1 in the shared.pgoff case, or
a multiple of PAGE_SIZE in the private.uaddr case (private.uaddr =
uaddr >> PAGE_SHIFT might make more sense). Whereas both.offset
would be a multiple of 4. I don't suppose Mr Jenkins will mind,
but I did find the "/4" puzzling in that context.
Hugh
next prev parent reply other threads:[~2003-09-08 17:31 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-05 20:24 today's futex changes Ulrich Drepper
2003-09-05 22:24 ` Stephen Hemminger
2003-09-06 16:28 ` [PATCH] " Hugh Dickins
2003-09-06 17:32 ` Ulrich Drepper
2003-09-06 17:44 ` Jamie Lokier
2003-09-06 17:46 ` Jamie Lokier
2003-09-06 18:21 ` Hugh Dickins
2003-09-08 6:45 ` Rusty Russell
2003-09-08 17:33 ` Hugh Dickins [this message]
2003-09-08 17:51 ` Hugh Dickins
2003-09-09 1:37 ` Rusty Russell
2003-09-08 17:51 ` Jamie Lokier
2003-09-08 18:26 ` Jamie Lokier
2003-09-09 3:58 ` Rusty Russell
2003-09-10 11:39 ` Jamie Lokier
2003-09-10 22:00 ` Rusty Russell
2003-09-11 16:29 ` Jamie Lokier
2003-09-08 19:02 ` Andrew Morton
2003-09-08 20:07 ` Jamie Lokier
2003-09-08 19:59 ` Andrew Morton
2003-09-08 20:11 ` Linus Torvalds
2003-09-09 4:12 ` Rusty Russell
2003-09-08 17:04 ` Stephen Hemminger
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