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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 9264EC2B9F8 for ; Mon, 24 May 2021 23:51:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78E0B613F9 for ; Mon, 24 May 2021 23:51:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229798AbhEXXxK (ORCPT ); Mon, 24 May 2021 19:53:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47006 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229819AbhEXXxJ (ORCPT ); Mon, 24 May 2021 19:53:09 -0400 Received: from mail-wm1-x333.google.com (mail-wm1-x333.google.com [IPv6:2a00:1450:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D452C06138A for ; Mon, 24 May 2021 16:51:40 -0700 (PDT) Received: by mail-wm1-x333.google.com with SMTP id u5-20020a7bc0450000b02901480e40338bso733074wmc.1 for ; Mon, 24 May 2021 16:51:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=klUJPrKjXipoTc2jn0OCW7ocxfKxOS9Q/bwu2HA5+Y0=; b=bBgt19vJhS2LAQboMMkYrXrqGE7vKnqaLzV2Imi5Mj9aDilGIYWNopdu72Zihyh9vi +/st9D7eXy/gWfW/0BYk4C7C0UnZRzqPWsXnNrxjv38oHvoupn0VhWVGRnT7MBeyI9B6 Sj8YyMtU+JIXMS1Q/XvfAQ1Jh7y2t20GxZCsdy03riEY3xs/Ve3Xt1xb/QCRKLLmpV1D SgnwcBC+1NF836F8wAhZtLdSsfbqnoiL4QYeYuhbCRgx+vYOjtFbSK3qMVsUOFrZwEV4 o6+4IhMbtulcUAV2XRNaUMBkhTeNQIycBKsmVfsDgM4+gtXyef8m4ZFvm6v9nFd65kte U2aA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=klUJPrKjXipoTc2jn0OCW7ocxfKxOS9Q/bwu2HA5+Y0=; b=kFy2PJl7dloldsBkJo0nUtt/cduu6dGJPDbGMZYfPAUnwyIrbfXs+Yv3uRDSfGFBnB Z8vCozX4qdRpr4WoloKqkwUhYIUz5etcxqM8O0KvkrCxTg+KVzRhQIj7yGr9ydZho6eW GDle0eCljQmA5nUXyl+u2c442ivTq2/qSz65mx/WVz1It3CcFvYjwmY4euyzD+eIV7wa 3VfkkjqtrfnSPT9wFC/3mrHDYeEoWnkdFwbC4bH4shnwDjOaHdR6JkXkGxe1H9oqUjMb 5/uqohpZhIShq801+g/bgPoE+gstEhgwrYq260LG4TE/6F1PmOWOn5KMIkWptHjkF4ve J+dA== X-Gm-Message-State: AOAM532V/08LkoZaLoTKoSDFMU1gmzk1cJwpDhDAMLBDvKtWjLhRc0Ze bOdS3PMzuuIlZPrSLaKMOwQ= X-Google-Smtp-Source: ABdhPJyHSYGN3v+TZx+4saRUqau0RWyE0OL/JPUlLpGyG+Q63aD/Cmxd1lLoU2XPRkdUEUztqdhwhg== X-Received: by 2002:a05:600c:4f15:: with SMTP id l21mr21188704wmq.37.1621900298784; Mon, 24 May 2021 16:51:38 -0700 (PDT) Received: from localhost.localdomain ([85.255.235.116]) by smtp.gmail.com with ESMTPSA id f7sm8961069wmq.30.2021.05.24.16.51.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 May 2021 16:51:38 -0700 (PDT) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Subject: [PATCH 12/13] io_uring: cache task struct refs Date: Tue, 25 May 2021 00:51:11 +0100 Message-Id: X-Mailer: git-send-email 2.31.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org tctx in submission part is always synchronised because is executed from the task's context, so we can batch allocate tctx/task references and store them across syscall boundaries. It avoids enough of operations, including an atomic for getting task ref and a percpu_counter_add() function call, which still fallback to spinlock for large batching cases (around >=32). Should be good for SQPOLL submitting in small portions and coming at some moment bpf submissions. Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 2b2d70a58a87..a95d55a0f9be 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -110,6 +110,8 @@ IOSQE_IO_HARDLINK | IOSQE_ASYNC | \ IOSQE_BUFFER_SELECT) +#define IO_TCTX_REFS_CACHE_NR (1U << 10) + struct io_uring { u32 head ____cacheline_aligned_in_smp; u32 tail ____cacheline_aligned_in_smp; @@ -472,6 +474,7 @@ struct io_ring_ctx { struct io_uring_task { /* submission side */ + int cached_refs; struct xarray xa; struct wait_queue_head wait; const struct io_ring_ctx *last; @@ -6702,16 +6705,23 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx) static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) { + struct io_uring_task *tctx; int submitted = 0; /* make sure SQ entry isn't read before tail */ nr = min3(nr, ctx->sq_entries, io_sqring_entries(ctx)); - if (!percpu_ref_tryget_many(&ctx->refs, nr)) return -EAGAIN; - 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; + + percpu_counter_add(&tctx->inflight, refill); + refcount_add(refill, ¤t->usage); + tctx->cached_refs += refill; + } io_submit_state_start(&ctx->submit_state, nr); while (submitted < nr) { @@ -6737,12 +6747,10 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr) if (unlikely(submitted != nr)) { int ref_used = (submitted == -EAGAIN) ? 0 : submitted; - struct io_uring_task *tctx = current->io_uring; int unused = nr - ref_used; + current->io_uring->cached_refs += unused; percpu_ref_put_many(&ctx->refs, unused); - percpu_counter_sub(&tctx->inflight, unused); - put_task_struct_many(current, unused); } io_submit_state_end(&ctx->submit_state, ctx); @@ -7924,7 +7932,7 @@ static int io_uring_alloc_task_context(struct task_struct *task, struct io_uring_task *tctx; int ret; - tctx = kmalloc(sizeof(*tctx), GFP_KERNEL); + tctx = kzalloc(sizeof(*tctx), GFP_KERNEL); if (unlikely(!tctx)) return -ENOMEM; @@ -7944,13 +7952,11 @@ static int io_uring_alloc_task_context(struct task_struct *task, xa_init(&tctx->xa); init_waitqueue_head(&tctx->wait); - tctx->last = NULL; atomic_set(&tctx->in_idle, 0); atomic_set(&tctx->inflight_tracked, 0); task->io_uring = tctx; spin_lock_init(&tctx->task_lock); INIT_WQ_LIST(&tctx->task_list); - tctx->task_state = 0; init_task_work(&tctx->task_work, tctx_task_work); return 0; } @@ -7961,6 +7967,7 @@ void __io_uring_free(struct task_struct *tsk) WARN_ON_ONCE(!xa_empty(&tctx->xa)); WARN_ON_ONCE(tctx->io_wq); + WARN_ON_ONCE(tctx->cached_refs); percpu_counter_destroy(&tctx->inflight); kfree(tctx); @@ -9097,6 +9104,16 @@ static void io_uring_try_cancel(bool cancel_all) } } +static void io_uring_drop_tctx_refs(struct task_struct *task) +{ + struct io_uring_task *tctx = task->io_uring; + unsigned int refs = tctx->cached_refs; + + tctx->cached_refs = 0; + percpu_counter_sub(&tctx->inflight, refs); + put_task_struct_many(task, refs); +} + /* should only be called by SQPOLL task */ static void io_uring_cancel_sqpoll(struct io_sq_data *sqd) { @@ -9112,6 +9129,7 @@ static void io_uring_cancel_sqpoll(struct io_sq_data *sqd) WARN_ON_ONCE(!sqd || sqd->thread != current); + io_uring_drop_tctx_refs(current); atomic_inc(&tctx->in_idle); do { /* read completions before cancelations */ @@ -9149,6 +9167,7 @@ void __io_uring_cancel(struct files_struct *files) io_wq_exit_start(tctx->io_wq); /* make sure overflow events are dropped */ + io_uring_drop_tctx_refs(current); atomic_inc(&tctx->in_idle); do { /* read completions before cancelations */ -- 2.31.1