Re: [PATCH v2] qemu: add a max_core setting to qemu.conf for core dump size

[Martin Kletzander <mkletzan@xxxxxxxxxx>]

On Tue, Jul 12, 2016 at 10:12:36AM +0100, Daniel P. Berrange wrote:
> Currently the QEMU processes inherit their core dump rlimit
> from libvirtd, which is really suboptimal. This change allows
> their limit to be directly controller from qemu.conf instead.
> ---
>
> Changed in v2:
>
> - Allow use of string "unlimited"
>
> src/libvirt_private.syms           |  2 ++
> src/qemu/libvirtd_qemu.aug         |  1 +
> src/qemu/qemu.conf                 | 16 +++++++++++++++-
> src/qemu/qemu_conf.c               | 17 +++++++++++++++++
> src/qemu/qemu_conf.h               |  1 +
> src/qemu/qemu_process.c            |  1 +
> src/qemu/test_libvirtd_qemu.aug.in |  1 +
> src/util/vircommand.c              | 14 ++++++++++++++
> src/util/vircommand.h              |  1 +
> src/util/virprocess.c              | 36 ++++++++++++++++++++++++++++++++++++
> src/util/virprocess.h              |  1 +
> 11 files changed, 90 insertions(+), 1 deletion(-)

[...]

> diff --git a/src/qemu/libvirtd_qemu.aug b/src/qemu/libvirtd_qemu.aug
> index 8bc23ba..a8edc2b 100644
> --- a/src/qemu/libvirtd_qemu.aug
> +++ b/src/qemu/libvirtd_qemu.aug
> @@ -72,6 +72,7 @@ module Libvirtd_qemu =
>                  | bool_entry "set_process_name"
>                  | int_entry "max_processes"
>                  | int_entry "max_files"
> +                 | int_entry "max_core"

This should be expanded to allow "unlimited" as well.

>                  | str_entry "stdio_handler"
>
>    let device_entry = bool_entry "mac_filter"

[...]

> diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
> index 510cd9a..b730202 100644
> --- a/src/qemu/qemu_conf.h
> +++ b/src/qemu/qemu_conf.h
> @@ -148,6 +148,7 @@ struct _virQEMUDriverConfig {
>
>     unsigned int maxProcesses;
>     unsigned int maxFiles;
> +    unsigned long long maxCore;

This is not initialized anywhere, effectively making the limit default
to 0 IIUC.

[...]

> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
> index 09dd3c9..2b71445 100644
> --- a/src/util/virprocess.c
> +++ b/src/util/virprocess.c
> @@ -914,6 +914,42 @@ virProcessSetMaxFiles(pid_t pid ATTRIBUTE_UNUSED, unsigned int files)
> }
> #endif /* ! (HAVE_SETRLIMIT && defined(RLIMIT_NOFILE)) */
>
> +#if HAVE_SETRLIMIT && defined(RLIMIT_CORE)
> +int
> +virProcessSetMaxCoreSize(pid_t pid, unsigned long long bytes)
> +{
> +    struct rlimit rlim;
> +
> +    rlim.rlim_cur = rlim.rlim_max = bytes;

Shouldn't be this set to RLIM_INFINITY if "unlimited" was requested?
Not taht ULLONG_MAX would not be enough, it's just that it's rlim_t and
it would be nicer to use it as described.

Martin

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