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[73.241.217.19]) by smtp.gmail.com with ESMTPSA id z9sm2525690pjr.39.2020.06.30.07.55.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 30 Jun 2020 07:55:51 -0700 (PDT) Subject: Re: About sbitmap_bitmap_show() and cleared bits (was Re: [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap) To: John Garry , axboe@kernel.dk, linux-block@vger.kernel.org Cc: Hannes Reinecke , jejb@linux.ibm.com, martin.petersen@oracle.com, don.brace@microsemi.com, kashyap.desai@broadcom.com, sumit.saxena@broadcom.com, ming.lei@redhat.com, hare@suse.com, hch@lst.de, shivasharan.srikanteshwara@broadcom.com, linux-scsi@vger.kernel.org, esc.storagedev@microsemi.com, chenxiang66@hisilicon.com, megaraidlinux.pdl@broadcom.com References: <1591810159-240929-1-git-send-email-john.garry@huawei.com> <1591810159-240929-8-git-send-email-john.garry@huawei.com> <9f4741c5-d117-d764-cf3a-a57192a788c3@suse.de> <7ed6ccf1-6ad9-1df7-f55d-4ed6cac1e08d@suse.de> <8ffd5c22-f644-3436-0a9f-2e08c220525e@huawei.com> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <8dfd5434-674a-5df6-114b-59cfed22588d@acm.org> Date: Tue, 30 Jun 2020 07:55:49 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <8ffd5c22-f644-3436-0a9f-2e08c220525e@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2020-06-29 08:32, John Garry wrote: > I noticed that sbitmap_bitmap_show() only shows set bits and does not > consider cleared bits. Is that the proper thing to do? > > I ask, as from trying to support sbitmap_bitmap_show() for hostwide > shared tags feature, we currently use blk_mq_queue_tag_busy_iter() to > find active requests (and associated tags/bits) for a particular hctx. > So, AFAICT, would give a change in behavior for sbitmap_bitmap_show(), > in that it would effectively show set and not cleared bits. > > Any thoughts on this? Probably this is something that got overlooked when the cleared bits were introduced? See e.g. 8c2def893afc ("sbitmap: fix sbitmap_for_each_set()"). Bart.