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Date: Sat, 8 Jan 2011 09:01:36 -0500 From: Tejun Heo <tj@...nel.org> To: Hillf Danton <dhillf@...il.com> Cc: linux-kernel@...r.kernel.org Subject: Re: [PATCH] replace ida in workqueue with page-sized buffer Hello, On Sat, Dec 18, 2010 at 09:10:18PM +0800, Hillf Danton wrote: > The id of worker of global work queue is monitored with kernel library, ida. > > The ida in global work queue is redefined to be page-sized buffer, > which is allocated when initializing workqueue. > > The new id allocator could monitor ids in the rage from 0 to INT_MAX. > The buffer is used to store freed ids, and if the peak number of ids, > in workqueue as whole, is not out of the capacity of the allocated > buffer, there is no more allocation of buffer after initializing. > > The advantage looks that the new allocator runs faster. I'm confused about why this is necessary. It's not like workqueue ID alloc/dealloc is hot path to begin with (they're quite lazy) and during worker creation / destruction ida is a quite insignificant part, so what is it trying to optimize? It's not like ida allocator is slow to begin with. Also, the allocator looks quite dubious. * What happens if more entries than what can fit in a page are freed? It'll just lose track of it. * ida guarantees that always the lowest available slot is allocated. The new allocator doesn't. So, why oh why? -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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