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Message-ID: <38b2ab8a0805260157k14d9a64dkeef48d230b978cf4@mail.gmail.com> Date: Mon, 26 May 2008 10:57:54 +0200 From: "Francis Moreau" <francis.moro@...il.com> To: "Jeff Garzik" <jeff@...zik.org> Cc: linux-kernel@...r.kernel.org, jens.axboe@...cle.com Subject: Re: question about splice performance Hello, On Sun, May 25, 2008 at 10:47 PM, Jeff Garzik <jeff@...zik.org> wrote: > > If you drop caches you are not measuring splice speed. > > Use ramfs for your tests (guarantees data is in cache) instead. > So it seems that the gain when using splice to copy a file into another file is very limited. Maybe that's the reason why cp is still using read/write... Also splice-cp uses 2 calls to splice syscall in a loop. So it end up doing a lot of syscalls. Maybe using sendfile instead of is better. Also2, since splice is a generalized pipe, it might be better to create to processes, one writing to the pipe and the other one reading to have better workflow. That said I also see some use cases where splice could be more useful, specially when one of the file descriptor is actually a device: one the write side of the pipes a device could write some data while on the other side of the pipe a process can empty the pipe by writing the data to a file. Are there any plans to improve splice interface to be used by drivers ? Thanks. -- Francis -- 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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