Date: Tue, 1 Jun 2010 11:41:09 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Kostik Belousov <kostikbel@gmail.com>, Dmitry Marakasov <amdmi3@amdmi3.ru>, freebsd-stable@freebsd.org Subject: Re: need better POSIX semaphore support Message-ID: <201006011141.09699.jhb@freebsd.org> In-Reply-To: <20100530150622.GJ83316@deviant.kiev.zoral.com.ua> References: <20100530143034.GH43302@hades.panopticon> <20100530150622.GJ83316@deviant.kiev.zoral.com.ua>
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On Sunday 30 May 2010 11:06:22 am Kostik Belousov wrote: > On Sun, May 30, 2010 at 06:30:35PM +0400, Dmitry Marakasov wrote: > > Hi! > > > > Not long ago, POSIX semaphores support was enabled by default as it's > > becoming more widely used, by e.g. firefox. However, the support > > for these is still incomplete: we only have systemwide limit of 30 > > semaphores, and that doesn't seem to be configurable neither online with > > sysctl, nor at boottime from loader.conf. I only was able to raise > > semaphore count by changing SEM_MAX in kernel sources. > > > > The real appliaction which needs more semaphores is lightspark > > (graphics/lightspark-devel) flash plugin - it uses ~40 sems for simple > > clips and ~250 for something like youtube videos. > > > > Until there more apps that require proper semaphore support, I guess > > we need to improve it asap. Given the amount of memory used by ksem, > > the least can be done is SEM_MAX bumped up to 5120 or so for > > non-embedded kernels. 5120 semaphores require just 644k of kernel > > memory (judging by vmstat), and is "ought to be enough for anybody". > > Another good thing would be to make it configurable at boot-time > > or even better in runtime. > > HEAD contains different implementation. Apparently, it did not made > into stable/8 yet, so it will not appear in the 8.1. The one thing I don't like about this approach is you can write the variable even when sem.ko isn't loaded. The SEM_* values should really only exist when sem.ko is loaded I think, which requires moving them into uipc_sem.c. > Try this, I could try to squeeze it into 8.1. > > diff --git a/sys/kern/posix4_mib.c b/sys/kern/posix4_mib.c > index 5242b31..41e28da 100644 > --- a/sys/kern/posix4_mib.c > +++ b/sys/kern/posix4_mib.c > @@ -57,6 +57,9 @@ SYSCTL_DECL(_p1003_1b); > #define P1B_SYSCTL(num, name) \ > SYSCTL_INT(_p1003_1b, num, \ > name, CTLFLAG_RD, facility + num - 1, 0, ""); > +#define P1B_SYSCTL_RW(num, name) \ > +SYSCTL_INT(_p1003_1b, num, \ > + name, CTLFLAG_RW, facility + num - 1, 0, ""); > > #else > > @@ -65,6 +68,9 @@ SYSCTL_DECL(_kern_p1003_1b); > #define P1B_SYSCTL(num, name) \ > SYSCTL_INT(_kern_p1003_1b, OID_AUTO, \ > name, CTLFLAG_RD, facility + num - 1, 0, ""); > +#define P1B_SYSCTL_RW(num, name) \ > +SYSCTL_INT(_kern_p1003_1b, OID_AUTO, \ > + name, CTLFLAG_RW, facility + num - 1, 0, ""); > SYSCTL_NODE(_kern, OID_AUTO, p1003_1b, CTLFLAG_RW, 0, "P1003.1B"); > > #endif > @@ -91,7 +97,7 @@ P1B_SYSCTL(CTL_P1003_1B_DELAYTIMER_MAX, delaytimer_max); > P1B_SYSCTL(CTL_P1003_1B_MQ_OPEN_MAX, mq_open_max); > P1B_SYSCTL(CTL_P1003_1B_PAGESIZE, pagesize); > P1B_SYSCTL(CTL_P1003_1B_RTSIG_MAX, rtsig_max); > -P1B_SYSCTL(CTL_P1003_1B_SEM_NSEMS_MAX, sem_nsems_max); > +P1B_SYSCTL_RW(CTL_P1003_1B_SEM_NSEMS_MAX, sem_nsems_max); > P1B_SYSCTL(CTL_P1003_1B_SEM_VALUE_MAX, sem_value_max); > P1B_SYSCTL(CTL_P1003_1B_SIGQUEUE_MAX, sigqueue_max); > P1B_SYSCTL(CTL_P1003_1B_TIMER_MAX, timer_max); > -- John Baldwin
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