Re: [PATCH] meson: improve CPU affinity routines check

Martin Kletzander wrote: > On Sun, Nov 21, 2021 at 07:58:55PM +0400, Roman Bogorodskiy wrote: > >Recently, FreeBSD has got sched_get/setaffinity(3) implementations and > >the sched.h header as well [1]. To make these routines visible, > >users have to define _WITH_CPU_SET_T. > > > >This breaks current detection. Specifically, meson sees the > >sched_getaffinity() symbol and defines WITH_SCHED_GETAFFINITY. This > >define unlocks Linux implementation of virProcessSetAffinity() and other > >functions, which fails to build on FreeBSD because cpu_set_t is not > >visible as _WITH_CPU_SET_T is not defined. > > > >For now, change detection to the following: > > > > - Instead of checking sched_getaffinity(), check if 'cpu_set_t' is > > available through sched.h > > - Explicitly check the sched.h header instead of assuming its presence > > if WITH_SCHED_SETSCHEDULER is defined > > > > Makes sense, although even the sched_getaffinity() is guarded by the new > _WITH_CPU_SET_T so there should be no error with the current code, am I Nope, as I tried to explain in the commit message, the current code is not working properly as it's using cc.has_function() for 'sched_getaffinity' and this check passes because it's checking the specified function in the standard library, so it works regardless of _WITH_CPU_SET_T. And as it finds the sched_getaffinity(), the build still fails because we don't set _WITH_CPU_SET_T.

> right? And if I understand correctly we cannot use the FreeBSD > implementation as is because they do not have all the CPU_* macros we > need, right? Frankly speaking, I haven't yet tested this implementation. Currently, virprocess.c is using the original FreeBSD interface: cpuset_(get|set)affinity. Generally, it would be a good thing to use the same implementation for both Linux and FreeBSD, however, this Linux-compatible interface in FreeBSD is not yet available in any FreeBSD release, so we'll have to keep the old code for some time anyway, and also I need to test if it actually works for us and figure out how to better detect and pass this _WITH_CPU_SET_T with meson.

> >1: > >https://cgit.freebsd.org/src/commit/?id=43736b71dd051212d5c55be9fa21c45993017fbb > >https://cgit.freebsd.org/src/commit/?id=160b4b922b6021848b6b48afc894d16b879b7af2 > >https://cgit.freebsd.org/src/commit/?id=90fa9705d5cd29cf11c5dc7319299788dec2546a > > > >Signed-off-by: Roman Bogorodskiy <bogorodskiy(a)gmail.com&gt; > >--- > > meson.build | 4 +++- > > src/util/virprocess.c | 8 ++++---- > > 2 files changed, 7 insertions(+), 5 deletions(-) > > > >diff --git a/meson.build b/meson.build > >index 9022bcfdc9..e4f36e8574 100644 > >--- a/meson.build > >+++ b/meson.build > >@@ -553,7 +553,6 @@ functions = [ > > 'posix_fallocate', > > 'posix_memalign', > > 'prlimit', > >- 'sched_getaffinity', > > 'sched_setscheduler', > > 'setgroups', > > 'setns', > >@@ -602,6 +601,7 @@ headers = [ > > 'net/if.h', > > 'pty.h', > > 'pwd.h', > >+ 'sched.h', > > 'sys/auxv.h', > > 'sys/ioctl.h', > > 'sys/mount.h', > >@@ -671,6 +671,8 @@ symbols = [ > > > > # Check for BSD approach for setting MAC addr > > [ 'net/if_dl.h', 'link_addr', '#include <sys/types.h>\n#include <sys/socket.h>' ], > >+ > >+ [ 'sched.h', 'cpu_set_t' ], > > ] > > > > if host_machine.system() == 'linux' > >diff --git a/src/util/virprocess.c b/src/util/virprocess.c > >index 6de3f36f52..81de90200e 100644 > >--- a/src/util/virprocess.c > >+++ b/src/util/virprocess.c > >@@ -35,7 +35,7 @@ > > # include <sys/time.h> > > # include <sys/resource.h> > > #endif > >-#if WITH_SCHED_SETSCHEDULER > >+#if WITH_SCHED_H > > # include <sched.h> > > #endif > > > >@@ -480,7 +480,7 @@ int virProcessKillPainfully(pid_t pid, bool force) > > return virProcessKillPainfullyDelay(pid, force, 0, false); > > } > > > >-#if WITH_SCHED_GETAFFINITY > >+#if WITH_DECL_CPU_SET_T > > > > int virProcessSetAffinity(pid_t pid, virBitmap *map, bool quiet) > > { > >@@ -626,7 +626,7 @@ virProcessGetAffinity(pid_t pid) > > return ret; > > } > > > >-#else /* WITH_SCHED_GETAFFINITY */ > >+#else /* WITH_DECL_CPU_SET_T */ > > > > int virProcessSetAffinity(pid_t pid G_GNUC_UNUSED, > > virBitmap *map G_GNUC_UNUSED, > >@@ -646,7 +646,7 @@ virProcessGetAffinity(pid_t pid G_GNUC_UNUSED) > > _("Process CPU affinity is not supported on this platform")); > > return NULL; > > } > >-#endif /* WITH_SCHED_GETAFFINITY */ > >+#endif /* WITH_DECL_CPU_SET_T */ > > > > > > int virProcessGetPids(pid_t pid, size_t *npids, pid_t **pids) > >-- > >2.33.1 > > Roman Bogorodskiy