linux-kernel - Re: [patch 6/13] signal/timer/event fds v7

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Date:	Mon, 19 Mar 2007 18:36:12 -0700 (PDT)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Eric Dumazet <dada1@...mosbay.com>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [patch 6/13] signal/timer/event fds v7 - timerfd core ...

On Tue, 20 Mar 2007, Eric Dumazet wrote:

> Davide Libenzi a écrit :
> 
> > +struct timerfd_ctx {
> > +	struct hrtimer tmr;
> > +	ktime_t tintv;
> > +	spinlock_t lock;
> > +	wait_queue_head_t wqh;
> > +	unsigned long ticks;
> > +};
> 
> > +static struct kmem_cache *timerfd_ctx_cachep;
> 
> > +	timerfd_ctx_cachep = kmem_cache_create("timerfd_ctx_cache",
> > +						sizeof(struct timerfd_ctx),
> > +						0, SLAB_PANIC, NULL, NULL);
> 
> 
> Do we really expect thousands of active timerfd_ctx ?
> 
> If not, using kmalloc()/kfree() would be fine, because sizeof(struct
> timerfd_ctx) is so small.
> 
> on SMP / NUMA platforms, each new kmem_cache is rather expensive. (memory
> allocated at kmem_cache_create(), but also memory used when cache is not
> empty, with slabs in freelist for each cpu/node)
> 
> Using a general cache might be cheaper : No memory overhead for yet another
> kmem_cache.
> 
> I know individual caches are good to spot memory leaks, but in timerfd case,
> you dont have mem leaks, do you ? :)

Silly you, of course not :)
Yes, I gues I can use kmalloc/kfree for those fds ...



- Davide