From: Thomas Monjalon <thomas@monjalon.net>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"Van Haaren, Harry" <harry.van.haaren@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"pbhagavatula@caviumnetworks.com"
<pbhagavatula@caviumnetworks.com>
Subject: Re: [dpdk-dev] [PATCH v2] test: fix debug autotest with eal cleanup addition
Date: Wed, 31 Jan 2018 15:31:41 +0100 [thread overview]
Message-ID: <10693804.qgnIZzW71k@xps> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB977258905663C3@IRSMSX103.ger.corp.intel.com>
31/01/2018 14:53, Ananyev, Konstantin:
> Hi Harry,
>
> From: Harry van Haaren
> >
> > Before this patch, the debug_autotest would call fork(),
> > call rte_panic() or rte_exit() in the child process, and
> > examine the return code to verify that rte_panic() and
> > rte_exit() were correctly reporting failures.
> >
> > With the inclusion of the rte_eal_cleanup() patch, rte_exit()
> > was modified to cleanly tear-down EAL allocations. Currently
> > only one library (service cores) is allocated by EAL at startup
> > and should be cleaned up. This library has a check on a normal
> > (non-hugepage) variable to protect against double cleanup. The
> > service cores finalize() function itself frees back hugepage mem.
> >
> > Given the fork() approach from the unit test, and the fact that
> > the double-free check is on an ordinary variable, causes multiple
> > child processed (fork()-ed from the unit-test runner) to attempt
> > to free the huge-page memory multiple times. The variable to
> > protect against double-cleanup was not effective, as the fork()
> > would restore it to show initialized in the next child.
> >
> > The solution is to call rte_service_finalize() *before* calling
> > fork(), which results in the service cores double-cleanup variable
> > to be zero before the fork(), and hence the child processes never
> > free the hugepage service-cores memory (correct behavior, as the
> > unit-test suite is still running, and owns the hugepages).
>
> Ok, you fixed it in UT, but what to do other apps that use fork()?
> Let say our examples/multi_process/l2fwd_fork uses fork() to
> spawn child processes instead of threads.
> Might be some generic way is needed: let say at fork time setup some
> global to indicate that it is a child process and it shouldn't call rte_finalize() or so.
> Konstantin
At first, we should discuss whether it is a good idea to support fork,
given that we have the "secondary process solution".
Then, if an improvement is needed, it should go in 18.05.
I think the fix in UT is good enough for 18.02.
next prev parent reply other threads:[~2018-01-31 14:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-30 18:21 [dpdk-dev] [PATCH] " Harry van Haaren
2018-01-30 18:26 ` [dpdk-dev] [PATCH v2] " Harry van Haaren
2018-01-30 23:53 ` Thomas Monjalon
2018-01-31 13:53 ` Ananyev, Konstantin
2018-01-31 14:31 ` Thomas Monjalon [this message]
2018-01-31 14:54 ` Van Haaren, Harry
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