http://dl.dropbox.com/u/7833186/libtcmalloc_minimal.dll.JPG (build directory
image) Is it possible that tcmalloc is used through this dll and the -U and
un-define prevent linking it statically?
________________________________
From: Moriz Gupte <moriz.gu...@gmail.com>
To: SLDEV <opensource-dev@lists.secondlife.com>
Sent: Monday, October 3, 2011 3:17 PM
Subject: Re: [opensource-dev] Mesh viewers and tcmalloc issues
Am wondering if anyone from Linden Lab can comment on this thread. This is such
an important issue regarding mesh viewers and mesh based economy. Many mesh
builders are reverting products back to sculpty versions because the majority
of clients refuse to use the latest viewers that support mesh because of the
significant fps drops.
On Mon, Oct 3, 2011 at 8:38 AM, Twisted Laws <twisted_l...@hotmail.com> wrote:
Only thing I don't understand about all this, is if you clone and build
viewer-development and 3p-google-perftools, then LL_USE_TCMALLOC is undefined
in both.
>
>in GooglePerfTools.cmake:
>
>set(TCMALLOC_FLAG -ULL_USE_TCMALLOC=1)
>
>and in llcommon property pages
>Undefine Preprocessor Definitions: LL_USE_TCMALLOC=1So it would appear, at
>least by default, that tcmalloc is not enabled. Am I understanding this
>wrong? Or does LL build their viewer with it defined and sending the viewer
>out the opensource world with it disabled?
>
>I did follow Henri's msg and built a viewer with
>EnvToDouble("TCMALLOC_RELEASE_RATE", 10000.0) (in 3p-google-perftools) and it
>seems to do exactly the same as without it.
>
>Twisted
> > Date: Sat, 1 Oct 2011 22:24:56 +0200
>> From: sl...@free.fr
>> To: opensource-dev@lists.secondlife.com
>> Subject: [opensource-dev] Mesh viewers and tcmalloc issues
>
>>
>> Greetings,
>>
>> I noticed that all the viewers using tcmalloc (mesh viewers under Linux
>> and Windows, since those use SSE2 and must gain memory-aligned malloc()
>> and new() calls that their standard library does not provide) suffer
>> from a serious problem: they never release memory back to the system,
>> meaning that after visiting a crowded place and caming around a lot,
>> the viewer can occupy 2.5Gb of memory, and even after you TP out to a
>> skybox with almost no objects/textures and no avatar around, the viewer
>> retains the full amount of alloctaed memory for itself.
>>
>> Worst, should you manage to keep the viewer from crashing during a full
>> hour or so, its allocated memory will get so badly fragmented that it
>> starts crawling down and finally crashes, even in quiet sims.
>>
>> Bao Linden recently worked on private memory pools to work around these
>> issues, but so far and despite his hard work, the result is less than
>> satisfactory: the memory is still never released to the system, and the
>> viewers using private memory pools crash every few minutes after issuing
>> a warning:
>> "LLPluginProcessParent::poll: apr_pollset_poll failed with status 4
>>
>> Well, be happy since I found an easy work around for these problems
>> while working on the Cool VL Viewer v1.26.1 (the mesh branch).
>>
>> tcmalloc is actually supposed to release back to the system the memory
>> freed by the application using it, but it does so only after a certain
>> number of memory blocks have been freed. There is an environment
>> variable that you can set (TCMALLOC_RELEASE_RATE) to adjust the "rate"
>> at which tcmalloc will release the freed blocks back to the system.
>> In fact, this is not really a rate, but a divisor (the number of freed
>> blocks is divided by the rate number (when != 0: a 0 rate means "never
>> release memory"), and compared to a threshold. If the number is below
>> the threshold, the freed blocks are released.
>> The documentation for tcmalloc says that "Reasonable rates are in the
>> range [0,10]", but even with a rate of 10, you never get the viewer to
>> release more than a couple hundreds megabytes for 2+Gb of allocated
>> memory. It occurred to me that the algorithm tcmalloc uses is simply
>> crippled !
>>
>> The good news, is that if you pass an "unreasonnable" rate, tcmalloc
>> will finally release memory (the more "unreasonnable" and the more
>> memory is released). With a rate of 10000 (yes, ten thousands), you
>> get the viewer to release everything when it doesn't need it any more,
>> which matches the behaviour of tcmalloc-less viewers.
>>
>> Since the Windows builds don't use a wrapper script to launch the
>> viewer, it is however best to hardcode this new rate as the default
>> one in tcmalloc istelf. This is what I did for the Cool VL Viewer
>> and it works like a charm. There is only one line to change in
>> tcmalloc source, in src/page_heap.cc:
>> DEFINE_double(tcmalloc_release_rate,
>> EnvToDouble("TCMALLOC_RELEASE_RATE", 10000.0), <--- HERE
>> "Rate at which we release unused memory to the system. "
>> "Zero means we never release memory back to the system. "
>> "Increase this flag to return memory faster; decrease it "
>> "to return memory slower. Reasonable rates are in the "
>> "range [0,10]");
>>
>> Now, the viewer runs rock stable (just like the non-mesh, tcmalloc-less
>> version) and uses very reasonnable amounts of memory. It also doesn't
>> suffer from memory fragmentation any more since it is transparently
>> taken care of by the OS (via the page table and the PMMU of the CPU,
>> something neither tcmalloc nor Bao's private memory pool can do since
>> these are userspace code).
>>
>> For what it is worth...
>>
>> Henri.
>> _______________________________________________
>> Policies and (un)subscribe information available here:
>> http://wiki.secondlife.com/wiki/OpenSource-Dev
>> Please read the policies before posting to keep unmoderated posting
>> privileges
>
>_______________________________________________
>Policies and (un)subscribe information available here:
>http://wiki.secondlife.com/wiki/OpenSource-Dev
>Please read the policies before posting to keep unmoderated posting privileges
>
--
'Consider how the lilies grow. They do not labor or spin.'
Rameshsharma Ramloll PhD, Research Associate Professor, Idaho State University,
Pocatello, ID 83209 Tel: 208-282-5333
Blog, LinkedIn, Play2Train
_______________________________________________
Policies and (un)subscribe information available here:
http://wiki.secondlife.com/wiki/OpenSource-Dev
Please read the policies before posting to keep unmoderated posting privileges_______________________________________________
Policies and (un)subscribe information available here:
http://wiki.secondlife.com/wiki/OpenSource-Dev
Please read the policies before posting to keep unmoderated posting privileges
