Messages in this thread | | | From | Vadim Lobanov <> | Subject | Re: [PATCH] fdtable: Eradicate fdarray overflow. | Date | Wed, 11 Oct 2006 23:07:38 -0700 |
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On Wednesday 11 October 2006 22:19, Eric Dumazet wrote: > Hi Vadim > > I find your PAGE_SIZE/4 minimum allocation quite unjustified. > > For architectures with 64K PAGE_SIZE, we endup allocating 16K, for poor > tasks that happen to touch a not so high (>= 64) file descriptor... > > I would vote for a fixed size, like 1024
In my opinion, always picking 1024 would be highly suboptimal for some architectures (x86-64 in particular -- that's a whole page, just for the fdarray!). If anything, I'd prefer something similar to this pseudo-code:
#define FDTABLE_MIN min_t(uint, PAGE_SIZE / 4 / sizeof(struct file *), 1024) ... nr /= FDTABLE_MIN; nr = roundup_pow_of_two(nr + 1); nr *= FDTABLE_MIN;
gcc should be smart enough to optimize that expression into a single constant. At least it did (version 4.1.0) in my quick test here.
> Eric
Let me know what you think. Please don't just go radio-silent on me. ;)
-- Vadim Lobanov - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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