Re: [PATCH] Improve scalability of epoll_ctl

[Changli Gao]

On Jan 9, 2008 12:56 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>
> Are you sure it's faster? vmalloc/vfree can be quite slow because
> they have to change the MMU state of the kernel and take global
> locks.
I don't think so. In fact, the memory of fdtable is allocated by
vmalloc when its size is bigger than PAGE_SIZE:

static inline void * alloc_fdmem(unsigned int size)
{
    if (size <= PAGE_SIZE)
        return kmalloc(size, GFP_KERNEL);
    else
        return vmalloc(size);
}

>
> The other problem is that on 32bit systems vmalloc space is somewhat
> limited -- you might have added an unintended scaling limit.

As I have talked above, I am sure open(), socket() and etc. will first
encounter it.

-- 
Regards，
Changli Gao(xiaosuo@xxxxxxxxx)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/