From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH 05/15] Add io_uring IO interface Date: Thu, 17 Jan 2019 13:14:09 -0700 Message-ID: <02568485-cd10-182d-98e3-619077cf9bdc@kernel.dk> References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> <718b4d1fbe9f97592d6d7b76d7a4537d@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: owner-linux-aio@kvack.org To: Jeff Moyer Cc: Roman Penyaev , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, avi@scylladb.com, linux-block-owner@vger.kernel.org List-Id: linux-arch.vger.kernel.org On 1/17/19 1:09 PM, Jens Axboe wrote: > On 1/17/19 1:03 PM, Jeff Moyer wrote: >> Jens Axboe writes: >> >>> On 1/17/19 5:48 AM, Roman Penyaev wrote: >>>> On 2019-01-16 18:49, Jens Axboe wrote: >>>> >>>> [...] >>>> >>>>> +static int io_allocate_scq_urings(struct io_ring_ctx *ctx, >>>>> + struct io_uring_params *p) >>>>> +{ >>>>> + struct io_sq_ring *sq_ring; >>>>> + struct io_cq_ring *cq_ring; >>>>> + size_t size; >>>>> + int ret; >>>>> + >>>>> + sq_ring = io_mem_alloc(struct_size(sq_ring, array, p->sq_entries)); >>>> >>>> It seems that sq_entries, cq_entries are not limited at all. Can nasty >>>> app consume a lot of kernel pages calling io_setup_uring() from a loop >>>> passing random entries number? (or even better: decreasing entries >>>> number, >>>> in order to consume all pages orders with min number of loops). >>> >>> Yes, that's an oversight, we should have a limit in place. I'll add that. >> >> Can we charge the ring memory to the RLIMIT_MEMLOCK as well? I'd prefer >> not to repeat the mistake of fs.aio-max-nr. > > Sure, we can do that. With the ring limited in size (it's now 4k entries > at most), the amount of memory gobbled up by that is much smaller than > the fixed buffers. A max sized ring is about 256k of memory. One concern here is that, at least looking at my boxes, the default setting for RLIMIT_MEMLOCK is really low. I'd hate for everyone to run into issues using io_uring just because it seems to require root, because the memlock limit is so low. That's much less of a concern with the fixed buffers, since it's a more esoteric part of it. But everyone should be able to setup a few io_uring queues and use them without having to worry about failing due to an absurdly low RLIMIT_MEMLOCK. Comments? -- Jens Axboe -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it1-f194.google.com ([209.85.166.194]:50443 "EHLO mail-it1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729381AbfAQUOM (ORCPT ); Thu, 17 Jan 2019 15:14:12 -0500 Received: by mail-it1-f194.google.com with SMTP id z7so3458581iti.0 for ; Thu, 17 Jan 2019 12:14:11 -0800 (PST) Subject: Re: [PATCH 05/15] Add io_uring IO interface From: Jens Axboe References: <20190116175003.17880-1-axboe@kernel.dk> <20190116175003.17880-6-axboe@kernel.dk> <718b4d1fbe9f97592d6d7b76d7a4537d@suse.de> Message-ID: <02568485-cd10-182d-98e3-619077cf9bdc@kernel.dk> Date: Thu, 17 Jan 2019 13:14:09 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Jeff Moyer Cc: Roman Penyaev , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, linux-block@vger.kernel.org, linux-arch@vger.kernel.org, hch@lst.de, avi@scylladb.com, linux-block-owner@vger.kernel.org Message-ID: <20190117201409.Mp98k3FtkxyGaslTEAS2wJFIeqK_K1CBGZADpb3AeyQ@z> On 1/17/19 1:09 PM, Jens Axboe wrote: > On 1/17/19 1:03 PM, Jeff Moyer wrote: >> Jens Axboe writes: >> >>> On 1/17/19 5:48 AM, Roman Penyaev wrote: >>>> On 2019-01-16 18:49, Jens Axboe wrote: >>>> >>>> [...] >>>> >>>>> +static int io_allocate_scq_urings(struct io_ring_ctx *ctx, >>>>> + struct io_uring_params *p) >>>>> +{ >>>>> + struct io_sq_ring *sq_ring; >>>>> + struct io_cq_ring *cq_ring; >>>>> + size_t size; >>>>> + int ret; >>>>> + >>>>> + sq_ring = io_mem_alloc(struct_size(sq_ring, array, p->sq_entries)); >>>> >>>> It seems that sq_entries, cq_entries are not limited at all. Can nasty >>>> app consume a lot of kernel pages calling io_setup_uring() from a loop >>>> passing random entries number? (or even better: decreasing entries >>>> number, >>>> in order to consume all pages orders with min number of loops). >>> >>> Yes, that's an oversight, we should have a limit in place. I'll add that. >> >> Can we charge the ring memory to the RLIMIT_MEMLOCK as well? I'd prefer >> not to repeat the mistake of fs.aio-max-nr. > > Sure, we can do that. With the ring limited in size (it's now 4k entries > at most), the amount of memory gobbled up by that is much smaller than > the fixed buffers. A max sized ring is about 256k of memory. One concern here is that, at least looking at my boxes, the default setting for RLIMIT_MEMLOCK is really low. I'd hate for everyone to run into issues using io_uring just because it seems to require root, because the memlock limit is so low. That's much less of a concern with the fixed buffers, since it's a more esoteric part of it. But everyone should be able to setup a few io_uring queues and use them without having to worry about failing due to an absurdly low RLIMIT_MEMLOCK. Comments? -- Jens Axboe