Re: [dpdk-dev] [PATCH v6 1/6] Move common functions in eal_thread.c

[Ravi Kerur <rkerur@gmail.com>]

On Tue, Apr 21, 2015 at 7:25 AM, Bruce Richardson <
bruce.richardson@intel.com> wrote:

> On Sat, Apr 18, 2015 at 12:43:06PM -0700, Ravi Kerur wrote:
> > Changes in v6
> > Remove RTE_EXEC_ENV_BSDAPP from eal_common_thread.c file.
> > Add pthread_setname_np/pthread_set_name_np for Linux/FreeBSD
> > respectively. Plan to use _getname_ in RTE_LOG when available.
> > Use existing rte_get_systid() in RTE_LOG to print thread_id.
>
> Hi Ravi
>
> I think the change to add names to the threads might be better in an
> existing
> patch as it is separate from the change of making the code common.
> [The code changes for the names also seems to have issues with it, as
> described in comments below]
>

Hi Bruce,

Thanks for your comments. Linux/FreeBSD has different APIs

pthread_setname_np and pthread_getname_np in Linux
pthread_set_name_np in FreeBSD. FreeBSD has no "_get_name_" counterpart API.

API signatures are different as well. Current plan is to use
"_setname_"/"_set_name_" appropriately and leave out "_getname_" until it
is available in FreeBSD.

Are you suggesting to use separate patch for set/get pthread names?

More inline.


> >
> > Changes in v5
> > Rebase to latest code.
> >
> > Changes in v4
> > None
> >
> > Changes in v3
> > Changed subject to be more explicit on file name inclusion.
> >
> > Changes in v2
> > None
> >
> > Changes in v1
> > eal_thread.c has minor differences between Linux and BSD, move
> > entire file into common directory.
> > Use RTE_EXEC_ENV_BSDAPP to differentiate on minor differences.
> > Rename eal_thread.c to eal_common_thread.c
> > Makefile changes to reflect file move and name change.
> > Fix checkpatch warnings.
> >
> > Signed-off-by: Ravi Kerur <rkerur@gmail.com>
> > ---
> >  examples/vhost/main.c                              |  18 ++-
> >  examples/vhost_xen/main.c                          |  18 ++-
> >  lib/librte_eal/bsdapp/eal/Makefile                 |   2 +-
> >  lib/librte_eal/bsdapp/eal/eal.c                    |   7 +
> >  lib/librte_eal/bsdapp/eal/eal_thread.c             | 152
> ---------------------
> >  lib/librte_eal/common/eal_common_thread.c          | 147
> +++++++++++++++++++-
> >  lib/librte_eal/common/eal_thread.h                 |   5 +
> >  lib/librte_eal/linuxapp/eal/Makefile               |   2 +
> >  lib/librte_eal/linuxapp/eal/eal.c                  |  10 ++
> >  lib/librte_eal/linuxapp/eal/eal_interrupts.c       |  11 ++
> >  lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c |  22 ++-
> >  lib/librte_eal/linuxapp/eal/eal_thread.c           | 152
> +--------------------
> >  lib/librte_eal/linuxapp/eal/eal_timer.c            |  15 +-
> >  13 files changed, 250 insertions(+), 311 deletions(-)
> >
>
> <<<snip>>>
>
> > --- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c
> > +++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio_mp_sync.c
> > @@ -34,6 +34,7 @@
> >  #include <string.h>
> >  #include <fcntl.h>
> >  #include <sys/socket.h>
> > +#include <pthread.h>
> >
> >  /* sys/un.h with __USE_MISC uses strlen, which is unsafe */
> >  #ifdef __USE_MISC
> > @@ -54,6 +55,7 @@
> >
> >  #include "eal_filesystem.h"
> >  #include "eal_pci_init.h"
> > +#include "eal_thread.h"
> >
> >  /**
> >   * @file
> > @@ -374,20 +376,36 @@ int
> >  pci_vfio_mp_sync_setup(void)
> >  {
> >       int ret;
> > +     char thread_name[RTE_THREAD_NAME_LEN];
> >
> >       if (vfio_mp_sync_socket_setup() < 0) {
> >               RTE_LOG(ERR, EAL, "Failed to set up local socket!\n");
> >               return -1;
> >       }
> >
> > +     snprintf(thread_name, RTE_THREAD_NAME_LEN,
> > +             "pci-vfio-mp-sync");
>
> This string is too long. According to the man page (Fedora Linux):
> "The thread name is a meaningful C language string, whose length is
> restricted to 16  charac‐
>        ters, including the terminating null byte ('\0')."
> I make the string 16+ null, i.e. 17 in total.
>

My mistake, will fix it.

>
> > +
> >       ret = pthread_create(&socket_thread, NULL,
> >                       pci_vfio_mp_sync_thread, NULL);
> >       if (ret) {
> > -             RTE_LOG(ERR, EAL, "Failed to create thread for
> communication with "
> > -                             "secondary processes!\n");
> > +             RTE_LOG(ERR, EAL,
> > +                     "Failed to create thread for communication with "
> > +                     "secondary processes!\n");
>
> Should not split the error message string across multiple lines as it
> breaks
> git grep searches for the error message.
>

Will fix it.

>
> > +             close(mp_socket_fd);
> > +             return -1;
> > +     }
> > +
> > +     ret = pthread_setname_np(socket_thread, thread_name);
> > +
> > +     if (ret) {
> > +             RTE_LOG(ERR, EAL,
> > +                     "Failed to set thread name for "
> > +                     "secondary processes!\n");
> >               close(mp_socket_fd);
> >               return -1;
>
> Do we really want to return with an error here. Right now I can't run any
> apps
> since I get an error on init of PCI - due to the name string being too
> long for
> Linux. (Things seem fine on BSD). Failing to name a thread doesn't seem to
> be
> a fatal error IMHO.
>
>
When I coded understanding was that pthread _set_ APIs should not fail
(excluding bugs whilst calling the API), since _get_ APIs will be called
subsequently for logging and debugging it will not be of any help if I let
program continue after _set_ failure. I will change the code to just log an
error and return success.

Thanks,
Ravi


> Regards,
> /Bruce
>
>