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Date: Mon, 10 Feb 2014 16:49:17 +0100 From: Alexander Gordeev <agordeev@...hat.com> To: Christoph Hellwig <hch@...radead.org> Cc: Kent Overstreet <kmo@...erainc.com>, Jens Axboe <axboe@...nel.dk>, Shaohua Li <shli@...nel.org>, linux-kernel@...r.kernel.org Subject: Re: [patch 1/2]percpu_ida: fix a live lock On Mon, Feb 10, 2014 at 01:29:42PM +0100, Alexander Gordeev wrote: > > We'll defintively need a fix to be able to allow the whole tag space. > > For large numbers of tags per device the flush might work, but for > > devices with low number of tags we need something more efficient. The > > case of less tags than CPUs isn't that unusual either and we probably > > want to switch to an allocator without per cpu allocations for them to > > avoid all this. E.g. for many ATA devices we just have a single tag, > > and many scsi drivers also only want single digit outstanding commands > > per LUN. > > Do we really always need the pool for these classes of devices? > > Pulling tags from local caches to the pool just to (near to) dry it at > the very next iteration does not seem beneficial. Not to mention caches > vs pool locking complexities. And I meant here we do not scrap per cpu allocations. -- Regards, Alexander Gordeev agordeev@...hat.com -- 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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