As Thomas said, false sharing would be a real issue with 96. So given a release is long due, at this point I'd say to drop this for the moment.
What do we do for the change to union for zmq_msg_t? Bump ABI version or not? On Thu, 2016-10-06 at 09:53 +0300, Doron Somech wrote: > No new socket type, I worked at the time on binary message type, might > complete it sometime, but it is not urgent. > > If there is a lot of performance penalty we can give it up, I will > find another solution for the Radio-Dish. > > What about 96 bytes? same penalty? > > Regarding the binding, I'm not sure. > > On Sat, Oct 1, 2016 at 9:14 PM, Luca Boccassi <luca.bocca...@gmail.com> wrote: > > On Tue, 2016-09-27 at 09:41 +0300, Doron Somech wrote: > >> Sorry for the late response, increasing the msg_t structure will be > >> great, however this will require changing a lot of binding. > > > > I think I remember we need it for the new socket types, is that correct? > > > > There is a large performance penalty (intuitively due to not fitting > > into a single cache line anymore, but haven't ran perf/cachegrind), and > > the throughput with vsm type messages goes down by 4% (min) and 20% > > (max) for TCP, and 36% (min) 38 (max) for inproc, which is quite a lot, > > so we need to be sure it's worth it. > > > > Regarding the bindings, after a quick search on the Github org, I could > > only see: > > > > https://github.com/zeromq/lzmq/blob/master/src/lua/lzmq/ffi/api.lua#L144 > > https://github.com/zeromq/clrzmq4/blob/master/lib/zmq.cs#L28 > > https://github.com/zeromq/pyczmq/blob/master/pyczmq/zmq.py#L177 > > > > Other bindings just import zmq.h. Did I miss any? > > > >> Sorry for disappearing, baby and full time job is a lot :-), hopefully > >> I'm back... > > > > No worries, perfectly understandable :-) > > > >> On Mon, Aug 29, 2016 at 6:46 PM, Luca Boccassi <luca.bocca...@gmail.com> > >> wrote: > >> > Sorry, I meant if we go with (1), not (2), we might bump the size as > >> > well, since we are already doing another ABI-breaking change. > >> > > >> > I agree on the solution as well. > >> > > >> > On Mon, 2016-08-29 at 17:12 +0200, Pieter Hintjens wrote: > >> >> I'm confused between the (1) and (2) choices, and can't see where > >> >> bumping the message size fits. > >> >> > >> >> Nonetheless, I think bumping the size, fixing the alignment issues, > >> >> and bumping the ABI version is the best solution here. > >> >> > >> >> On Fri, Aug 26, 2016 at 12:33 PM, Luca Boccassi > >> >> <luca.bocca...@gmail.com> wrote: > >> >> > I've given some more thoughts and testing to the alignment issue. I > >> >> > can > >> >> > reproduce the problem by enabling alignment checks on x86 too. > >> >> > > >> >> > But most importantly, I think we cannot get away from bumping the ABI > >> >> > with this fix, however we rearrange it, simply because applications > >> >> > need > >> >> > to be rebuilt against the new header to be fixed. A simple rebuild of > >> >> > the libzmq.so is not enough. And the way to do this is to bump the ABI > >> >> > so that distros can schedule transitions and rebuilds and so on. > >> >> > > >> >> > So the choice list is now restricted to: > >> >> > > >> >> > 1) Bump ABI > >> >> > 2) Revert the fix and leave everything broken on sparc64 and some > >> >> > aarch64 (rpi3 seems not to be affected, must depend on the SoC > >> >> > flavour) > >> >> > > >> >> > If we go with 2, we might as well get 2 birds with one stone and bump > >> >> > the zmq_msg_t size to 128 as we have talked about in the past. > >> >> > > >> >> > Doron, this would help with the new UDP based socket types right? > >> >> > > >> >> > Pros of bumping msg size: > >> >> > > >> >> > - we can get rid of the malloc() in the lmsg type case as all the data > >> >> > will fit > >> >> > > >> >> > Cons: > >> >> > > >> >> > - for the vsm/cmsg type cases (for most architectures anyway) it won't > >> >> > fit anymore into a single cacheline > >> >> > > >> >> > Given all this, I'd say we should go for it. > >> >> > > >> >> > Opinions? > >> >> > > >> >> > On Sat, 2016-08-13 at 16:59 +0100, Luca Boccassi wrote: > >> >> >> Hello, > >> >> >> > >> >> >> Trying to give some thoughts again on the libzmq 4.2 release. It's > >> >> >> really long overdue! > >> >> >> > >> >> >> The main issue from my point of view is this change: > >> >> >> > >> >> >> https://github.com/zeromq/libzmq/commit/d9fb1d36ff2008966af538f722a1f4ab158dbf64 > >> >> >> > >> >> >> -typedef struct zmq_msg_t {unsigned char _ [64];} zmq_msg_t; > >> >> >> +/* union here ensures correct alignment on architectures that > >> >> >> require > >> >> >> it, e.g. > >> >> >> + * SPARC > >> >> >> + */ > >> >> >> +typedef union zmq_msg_t {unsigned char _ [64]; void *p; } > >> >> >> zmq_msg_t; > >> >> >> > >> >> >> > >> >> >> This is flagged by the common ABI checkers tools as an ABI breakage > >> >> >> (see: http://abi-laboratory.pro/tracker/timeline/zeromq/ ). And it > >> >> >> makes > >> >> >> sense from this point of view: if some applications on some > >> >> >> architectures are broken due to wrong alignment, they would need to > >> >> >> be > >> >> >> rebuilt, and the way to ensure that is to bump the ABI "current" > >> >> >> digit > >> >> >> to make sure maintainers do a rebuild. > >> >> >> > >> >> >> On the other hand, signaling an ABI breakage is a pain, and a cause > >> >> >> of > >> >> >> major churn for packagers and maintainers. It means for example a new > >> >> >> package has to be created (eg: libzmq5 -> libzmq6), and a transition > >> >> >> has > >> >> >> to be started and all reverse dependencies need to be rebuilt. And if > >> >> >> this is pointless for all save a few corner cases (eg SPARC64 as for > >> >> >> above) it's all quite frustrating. > >> >> >> > >> >> >> So we have a choice to make before we release 4.2, four > >> >> >> possibilities as > >> >> >> far as I can see: > >> >> >> > >> >> >> 1) Ignore the ABI checkers and get yelled at by maintainers and > >> >> >> packagers. Also the SPARC64 users will most likely NOT get their bug > >> >> >> fixed > >> >> >> 2) Bump ABI revision to 6 and get yelled at by maintainers and > >> >> >> packagers > >> >> >> 3) Revert the above change and postpone it to when we have a more > >> >> >> generally useful reason to break ABI (bump zmq_msg_t from 64 to 128 > >> >> >> bytes for example, Doron?) > >> >> >> 4) Try to be clever and revert the above change and use something > >> >> >> like > >> >> >> #pragma pack(8). This will fool the ABI checkers (I tried it), and > >> >> >> given > >> >> >> that typedef is only used externally to allocate the right size it > >> >> >> shouldn't actually affect anything, apart from the users of SPARC64 > >> >> >> which should get the bugfix with this too. This is very sneaky :-) > >> >> >> > >> >> >> CC'ing Lazslo, the Debian maintainer, given what we choose to do > >> >> >> might > >> >> >> result in a lot of work for him :-) > >> >> >> > >> >> >> Opinions? > >> >> >> > >> >> >> Kind regards, > >> >> >> Luca Boccassi > >> >> >> > >> >> >> On Tue, 2016-05-03 at 10:39 +0200, Pieter Hintjens wrote: > >> >> >> > Hi all, > >> >> >> > > >> >> >> > I'm just throwing some ideas on the table. We have a good package > >> >> >> > of > >> >> >> > work on master and it's probably time to make a 4.2 release. > >> >> >> > > >> >> >> > Luca has already back-ported the enable/disable draft design from > >> >> >> > zproject (CZMQ et al). Yay! So we can now release stable master > >> >> >> > safely, while continuing to refine and extend the draft API > >> >> >> > sections. > >> >> >> > > >> >> >> > I propose: > >> >> >> > > >> >> >> > - to end with the stable fork policy; this was needed years ago > >> >> >> > when > >> >> >> > we had massively unstable masters. It's no longer a problem. > >> >> >> > - to use the github release function for libzmq releases and > >> >> >> > deprecate > >> >> >> > the separate delivery of tarballs. > >> >> >> > - we aim to make a 4.2.0 rc asap, then fix any issues we get, with > >> >> >> > patch releases as usual. > >> >> >> > - we backport the release function to older maintained releases > >> >> >> > (4.1, > >> >> >> > 3.2) so that their tarballs are provided by github instead of > >> >> >> > downloads.zeromq.org. > >> >> >> > > >> >> >> > Problems: > >> >> >> > > >> >> >> > - this will break a few things that depend on > >> >> >> > downloads.zeromq.org. To > >> >> >> > be fixed as we go. > >> >> >> > - github tarballs are not identical to source tarballs, > >> >> >> > particularly > >> >> >> > they lack `configure`. I propose changing our autotools build > >> >> >> > instructions so they always start with `./autogen,sh` no matter > >> >> >> > where > >> >> >> > the sources come from. > >> >> >> > > >> >> >> > I think this will work and also let us gracefully deprecate/switch > >> >> >> > off > >> >> >> > the downloads box. > >> >> >> > > >> >> >> > -Pieter > >> >> >> > _______________________________________________ > >> >> >> > zeromq-dev mailing list > >> >> >> > zeromq-dev@lists.zeromq.org > >> >> >> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > >> >> >> > >> >> >> > >> >> > > >> >> > > >> >> > > >> >> > _______________________________________________ > >> >> > zeromq-dev mailing list > >> >> > zeromq-dev@lists.zeromq.org > >> >> > http://lists.zeromq.org/mailman/listinfo/zeromq-dev > >> >> _______________________________________________ > >> >> zeromq-dev mailing list > >> >> zeromq-dev@lists.zeromq.org > >> >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev > >> > > >> > > >
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