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AJvYcCX2yrLTdo+Ijiw7oaQ0imPSPzB+62C1VFKw9w+9H1MatbaMLiIkrQoKhREUrJm8abwlD7dVRPAPhwk7zhsoslzYW6aQcamsUC0= X-Gm-Message-State: AOJu0Yz75zg2ItDeIx6Fg2pjSK5jiJWT/4ccEczhJlDhEq8R2V8lCBbb RnFTy7NIyXiUNHAemr6EbT1SiGi3VEdH37pxLciBu4oKZn2+qIX/vo7tFzGSeQY= X-Google-Smtp-Source: AGHT+IF8xWEgjz4aEgsmi6V88eLgJoCTfJSDZaQ30pMgkIbaxDvfIYVaJFyK2T46SzElSkBCkgY9zw== X-Received: by 2002:a6b:f801:0:b0:7cb:f105:57a5 with SMTP id o1-20020a6bf801000000b007cbf10557a5mr2508973ioh.1.1710520071049; Fri, 15 Mar 2024 09:27:51 -0700 (PDT) Received: from [192.168.1.116] ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id gc12-20020a056638670c00b004775d1fd781sm269586jab.145.2024.03.15.09.27.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 Mar 2024 09:27:50 -0700 (PDT) Message-ID: Date: Fri, 15 Mar 2024 10:27:49 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 11/11] io_uring: get rid of intermediate aux cqe caches Content-Language: en-US From: Jens Axboe To: Pavel Begunkov , io-uring@vger.kernel.org Cc: linux-block@vger.kernel.org, Kanchan Joshi , Ming Lei References: <0eb3f55722540a11b036d3c90771220eb082d65e.1710514702.git.asml.silence@gmail.com> <6e5d55a8-1860-468f-97f4-0bd355be369a@kernel.dk> <7a6b4d7f-8bbd-4259-b1f1-e026b5183350@gmail.com> <70e18e4c-6722-475d-818b-dc739d67f7e7@kernel.dk> In-Reply-To: <70e18e4c-6722-475d-818b-dc739d67f7e7@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/15/24 10:25 AM, Jens Axboe wrote: > On 3/15/24 10:23 AM, Pavel Begunkov wrote: >> On 3/15/24 16:20, Jens Axboe wrote: >>> On 3/15/24 9:30 AM, Pavel Begunkov wrote: >>>> io_post_aux_cqe(), which is used for multishot requests, delays >>>> completions by putting CQEs into a temporary array for the purpose >>>> completion lock/flush batching. >>>> >>>> DEFER_TASKRUN doesn't need any locking, so for it we can put completions >>>> directly into the CQ and defer post completion handling with a flag. >>>> That leaves !DEFER_TASKRUN, which is not that interesting / hot for >>>> multishot requests, so have conditional locking with deferred flush >>>> for them. >>> >>> This breaks the read-mshot test case, looking into what is going on >>> there. >> >> I forgot to mention, yes it does, the test makes odd assumptions about >> overflows, IIRC it expects that the kernel allows one and only one aux >> CQE to be overflown. Let me double check > > Yeah this is very possible, the overflow checking could be broken in > there. I'll poke at it and report back. It does, this should fix it: diff --git a/test/read-mshot.c b/test/read-mshot.c index 8fcb79857bf0..501ca69a98dc 100644 --- a/test/read-mshot.c +++ b/test/read-mshot.c @@ -236,7 +236,7 @@ static int test(int first_good, int async, int overflow) } if (!(cqe->flags & IORING_CQE_F_MORE)) { /* we expect this on overflow */ - if (overflow && (i - 1 == NR_OVERFLOW)) + if (overflow && i >= NR_OVERFLOW) break; fprintf(stderr, "no more cqes\n"); return 1; -- Jens Axboe