From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E53F5C47089 for ; Thu, 27 May 2021 22:13:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2925611C2 for ; Thu, 27 May 2021 22:13:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235680AbhE0WOp (ORCPT ); Thu, 27 May 2021 18:14:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40586 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233563AbhE0WOp (ORCPT ); Thu, 27 May 2021 18:14:45 -0400 Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17204C061574 for ; Thu, 27 May 2021 15:13:10 -0700 (PDT) Received: by mail-wr1-x435.google.com with SMTP id r10so1290165wrj.11 for ; Thu, 27 May 2021 15:13:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=GVDzzprZ5k10HW2MbqOv2I8vQVjVo52mBlBGQnANsGc=; b=mbOlDgGH5auTxshlQGJJfgR3aOrHB2hkG7tRv70XobQc2tcLztJf7Dce8OPB0wqouO swecaJg7tZdR/eF/nx2kYE5RYHZVO9lIlwk1k4Lbv9Eo5yrVlbazp1KsWzITc6HEVROs M4dDowZfZ6iWDp7rN0bCvvboIg//eZcGeBdlx0iA4CUN9kSFaRV9ptjiOvUV3aSt5efO ZNyeCNff5PzqNDRu1kC5+4jduw96hOT7AC4lI4b+CEKXN1H+RdU4n59ivFy6o7hJumGj 8S65Hm92t+3iHCmHG0iwHpt/lB3Q5MWHxGhawPjlB/WdVm+eXRewGpc/876cenWvgUOM PJVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=GVDzzprZ5k10HW2MbqOv2I8vQVjVo52mBlBGQnANsGc=; b=A6jTXevge1ygtboT72dHEwFnDziQBpoKtnI2bt3rOLSNyuqLyWjdLX8J0PgJDGmEVA H4ERnROogaSa2aWUCqcKx0scbaM0fC6qJkNEObJ9n5/XzvHcWL5ENNARQuMHIHLXvYR7 oGPT6cjvifM/KPjM8i71wuliHUWTFOvTLN7YQ1Ew15g0NDn6AbfHoHeafwqc6vafzDr/ 1ThpsKD5BEWjc9MJQG+QG7F8IKhMMS4usORBawS8TV6fEInlRdz9ERPOxKHZH05mKAHg ikoWn5JurinePkPIrrIqgui3p9jD0e9YkZyAwUQc1UTBBjVf1LbDaBtUvKq74aMk1Hen yKMg== X-Gm-Message-State: AOAM53119LqacQI/vi5vsSn2mUsKk3KKNodhF7koyeBrfD+NB6JZBIMQ iZl2V7cL9f0E81OOwWvmZ9/G7oVhR0ndQoqi X-Google-Smtp-Source: ABdhPJwSclvqhnr2u5GbIAFq/KGWNKfCW2Ws1zjCENXadUuXEKV71/2KnYf6sY+tFlTMYXUv8fCWsg== X-Received: by 2002:a05:6000:22a:: with SMTP id l10mr3574760wrz.171.1622153588513; Thu, 27 May 2021 15:13:08 -0700 (PDT) Received: from [192.168.8.197] ([148.252.129.19]) by smtp.gmail.com with ESMTPSA id n13sm5337071wrg.75.2021.05.27.15.13.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 May 2021 15:13:08 -0700 (PDT) Subject: Re: [PATCH 12/13] io_uring: cache task struct refs To: Noah Goldstein Cc: Jens Axboe , "open list:IO_URING" References: From: Pavel Begunkov Message-ID: <5ec6ff35-50ba-2938-483e-449a4560af65@gmail.com> Date: Thu, 27 May 2021 23:13:00 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 5/27/21 10:51 PM, Noah Goldstein wrote: > On Mon, May 24, 2021 at 7:51 PM Pavel Begunkov wrote: [...] >> >> - percpu_counter_add(¤t->io_uring->inflight, nr); >> - refcount_add(nr, ¤t->usage); >> + tctx = current->io_uring; >> + tctx->cached_refs -= nr; >> + if (unlikely(tctx->cached_refs < 0)) { >> + unsigned int refill = -tctx->cached_refs + IO_TCTX_REFS_CACHE_NR; > > Might be cleared to use: > > unsigned int refill = IO_TCTX_REFS_CACHE_NR - tctx->cached_refs; ======================================================================= Did think about it, but left as is to emphasize that it's negative and we convert it to positive, so all operations are with positive (and unsigned due to C rules). Code generation will be same. >> + >> + percpu_counter_add(&tctx->inflight, refill); >> + refcount_add(refill, ¤t->usage); >> + tctx->cached_refs += refill; >> + } >> io_submit_state_start(&ctx->submit_state, nr); >> -- Pavel Begunkov