Hi Elias, As mentioned by Dave, running Valgrind on VPP is challenging because of speed and custom allocators. That being said, I am (slowly) working on integrating Address Sanitizer into VPP. I have some cleanup to do but I can share my WIP patches if interested.
Best ben > -----Original Message----- > From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Dave Barach > via Lists.Fd.Io > Sent: lundi 9 septembre 2019 14:20 > To: Elias Rudberg <elias.rudb...@bahnhof.net>; vpp-dev@lists.fd.io > Cc: vpp-dev@lists.fd.io > Subject: Re: [vpp-dev] How to use valgrind to check for memory errors in > vpp? > > Dlmalloc [aka "Doug Lea Malloc"] is a lightly modified copy of the > allocator described here: http://gee.cs.oswego.edu/dl/html/malloc.html. If > you've managed to find an issue in it, please share the details. Until > proven otherwise, I suspect the report rather than dlmalloc itself. > > Vpp does indeed manage its own thread stacks. The so-called vpp process > model [in truth: cooperative multi-tasking threads] uses setjmp/longjmp to > switch stacks. The scheme is fundamental, and won't be changed to > accomodate valgrind. > > Dlmalloc does not support valgrind. It's a waste of a huge number of > cycles to run valgrind unless the memory allocator supports it. My > experience making vpp's previous memory allocator support valgrind might > be worth sharing: it never worked very well. After > 15 years working on > the code base, I've not felt the need to go back and make it work in > detail. > > Vpp uses multiple, independent heaps - some in shared memory - so > switching to vanilla malloc() seems like a non-starter. > > Vpp's virtual space is larger than one might like - note the difference > with none of the plugins loaded - but in terms of real memory consumption > we often see RSS sizes in the 20-30mb range. A decent fraction of the > virtual space is used to avoid expensive computations in device drivers: > to facilitate virtual <--> physical address translation. > > Any issues accidentally introduced into the memory allocator would be a > severe nuisance. Folks would be well-advised not to tinker with it. > > HTH... Dave > > -----Original Message----- > From: vpp-dev@lists.fd.io <vpp-dev@lists.fd.io> On Behalf Of Elias Rudberg > Sent: Monday, September 9, 2019 4:43 AM > To: vpp-dev@lists.fd.io > Subject: [vpp-dev] How to use valgrind to check for memory errors in vpp? > > Hello, > > I would like to use valgrind to check for memory errors in vpp. > > I understand that running something through valgrind makes it very very > slow so that it is not an option for real production usage of vpp. > However, valgrind is still very useful for finding errors even if it's > only for very limited test runs, so I would very much like to make that > work. > > I know that vpp has some built-in checking for memory leaks, but the > reason I want to use valgrind is not primarily to check for memory leaks > but to check for other kinds of memory-access-related errors, like the > "invalid read" and "invalid write" errors that valgrind can detect. > > So far, what I have done is to build vpp (debug configuration) according > to the instructions here: https://fdio- > vpp.readthedocs.io/en/latest/gettingstarted/developers/building.html > Then I stopped the vpp service since I want to run vpp from the command- > line through valgrind, and finally I run it like this: > > sudo valgrind vpp -c /etc/vpp/startup.conf > > That gave warnings about "client switching stacks?" and suggested adding - > -max-stackframe=137286291952 so I did that: > > sudo valgrind --max-stackframe=137286291936 vpp -c /etc/vpp/startup.conf > > Then valgrind gives a warning "Warning: set address range perms: large > range" followed by some error reports of the type "Conditional jump or > move depends on uninitialised value(s)" inside the mspace_malloc routine > in dlmalloc.c. > > I think these issues are probably related to the fact that vpp uses its > own malloc implementation (in dlmalloc.c) instead of the default malloc, > possibly combined with the fact that vpp uses very large (virual) memory. > > Questions: > > - Are there ways to configure vpp to allow it to work together with > valgrind? > > - Are there ways to make vpp use less memory? (currently "top" shows > 0.205t VIRT memory usage for the vpp_main process) > > - Is it possible to somehow configure vpp to use standard malloc instead > of the dlmalloc.c implementation, perhaps sacrificing performance but > making things work better with valgrind? > > Best regards, > Elias
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