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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 D28F0C4CECE for ; Sun, 13 Oct 2019 00:30:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A3D2E222BD for ; Sun, 13 Oct 2019 00:30:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="wP3VRc4S" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729018AbfJMAax (ORCPT ); Sat, 12 Oct 2019 20:30:53 -0400 Received: from mail-pg1-f201.google.com ([209.85.215.201]:52731 "EHLO mail-pg1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729003AbfJMAav (ORCPT ); Sat, 12 Oct 2019 20:30:51 -0400 Received: by mail-pg1-f201.google.com with SMTP id e15so9878491pgh.19 for ; Sat, 12 Oct 2019 17:30:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=P7abJRI85r+K/TRDAITrJhvU4blOks6xxJvHrDmdwNo=; b=wP3VRc4Sjd0MfiWZ3l2O6xPOLegcNe5EG1wD6mk6jKeio7RlfzqcFgBJyTj8r2Qle2 kuGJwA3jttSxlj7OKvvEPJdc3CKObPaqCoIxgSi2+gefihDO33R6kqlmnHH76TwNxMpG SLcYgJmC6zeZuTvcfSwzUAMb4vKCHShqf89n0eGQQIbfvZ280blHsZSwNsjdxgaXhUpQ ljle8dNBA64Hmq3eBKl6ld5wmof4nc8QdiozpMkmy+vjIrXPnnPjAImDGAKwjPoIZHw5 Ffr+GO/dLvKz03UQ1axTfrFlysqXhmwBXxxDdUJDi9DbQUmX73pfEtBtHLS0/xbo2JCd qzHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=P7abJRI85r+K/TRDAITrJhvU4blOks6xxJvHrDmdwNo=; b=IZjQe1F8svOqh/3T5LUQHFn/5gduwv9lL6RFY2weYaiIDk5ZEpLYsYAy2AvLR3P2fk f0QXHSDjzPbYclA9UyNgjfNCJriI6B/78mG+xbM4opZE+lr+BATpuULBGAu4Ox2IE+R9 RYhvMcm/E0NhIWW3RbXNv4i/ZTZfYnGfR/YtJLcJmqkKLtzaOsp8xIwJplqj1O8Zc+2s 83K2m+s1iPU2r8qA33e/cCvJjnmJvdo5jZTUZtMVpvTWTt2Z00UJozfyMS7dQW0iw7Bs 7y8AWNje0WJairddyWzz3chqjMZKCMJ4tIKIztqdnGDUkrgJxdt21gCudK2InWjpdN06 A06w== X-Gm-Message-State: APjAAAVWWMjPFgfEaH/7kMaTVjEVw8b0q1/jM/6PKPGXfwbK9swy5V9l pvtKwUjasiLACWR8C3btjDlB69NB/ZzBI0twKw== X-Google-Smtp-Source: APXvYqxXEc4NA7oKRRTcl220Dm4FauosfZDC5X4WT0geKI4r44dqc3LfO67JzAjlCIBC80vIy5yux4EZzO32zBDpPA== X-Received: by 2002:a63:cf4a:: with SMTP id b10mr23871724pgj.86.1570926649195; Sat, 12 Oct 2019 17:30:49 -0700 (PDT) Date: Sat, 12 Oct 2019 17:30:24 -0700 In-Reply-To: <20191013003024.215429-1-almasrymina@google.com> Message-Id: <20191013003024.215429-9-almasrymina@google.com> Mime-Version: 1.0 References: <20191013003024.215429-1-almasrymina@google.com> X-Mailer: git-send-email 2.23.0.700.g56cf767bdb-goog Subject: [PATCH v6 9/9] hugetlb_cgroup: Add hugetlb_cgroup reservation docs From: Mina Almasry To: mike.kravetz@oracle.com Cc: shuah@kernel.org, almasrymina@google.com, rientjes@google.com, shakeelb@google.com, gthelen@google.com, akpm@linux-foundation.org, khalid.aziz@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, cgroups@vger.kernel.org, aneesh.kumar@linux.vnet.ibm.com, mkoutny@suse.com, Hillf Danton Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add docs for how to use hugetlb_cgroup reservations, and their behavior. Signed-off-by: Mina Almasry Acked-by: Hillf Danton --- Changes in v6: - Updated docs to reflect the new design based on a new counter that tracks both reservations and faults. --- .../admin-guide/cgroup-v1/hugetlb.rst | 64 +++++++++++++++---- 1 file changed, 53 insertions(+), 11 deletions(-) diff --git a/Documentation/admin-guide/cgroup-v1/hugetlb.rst b/Documentation/admin-guide/cgroup-v1/hugetlb.rst index a3902aa253a96..efb94e4db9d5a 100644 --- a/Documentation/admin-guide/cgroup-v1/hugetlb.rst +++ b/Documentation/admin-guide/cgroup-v1/hugetlb.rst @@ -2,13 +2,6 @@ HugeTLB Controller ================== -The HugeTLB controller allows to limit the HugeTLB usage per control group and -enforces the controller limit during page fault. Since HugeTLB doesn't -support page reclaim, enforcing the limit at page fault time implies that, -the application will get SIGBUS signal if it tries to access HugeTLB pages -beyond its limit. This requires the application to know beforehand how much -HugeTLB pages it would require for its use. - HugeTLB controller can be created by first mounting the cgroup filesystem. # mount -t cgroup -o hugetlb none /sys/fs/cgroup @@ -28,10 +21,14 @@ process (bash) into it. Brief summary of control files:: - hugetlb..limit_in_bytes # set/show limit of "hugepagesize" hugetlb usage - hugetlb..max_usage_in_bytes # show max "hugepagesize" hugetlb usage recorded - hugetlb..usage_in_bytes # show current usage for "hugepagesize" hugetlb - hugetlb..failcnt # show the number of allocation failure due to HugeTLB limit + hugetlb..reservation_limit_in_bytes # set/show limit of "hugepagesize" hugetlb reservations + hugetlb..reservation_max_usage_in_bytes # show max "hugepagesize" hugetlb reservations and no-reserve faults. + hugetlb..reservation_usage_in_bytes # show current reservations and no-reserve faults for "hugepagesize" hugetlb + hugetlb..reservation_failcnt # show the number of allocation failure due to HugeTLB reservation limit + hugetlb..limit_in_bytes # set/show limit of "hugepagesize" hugetlb faults + hugetlb..max_usage_in_bytes # show max "hugepagesize" hugetlb usage recorded + hugetlb..usage_in_bytes # show current usage for "hugepagesize" hugetlb + hugetlb..failcnt # show the number of allocation failure due to HugeTLB usage limit For a system supporting three hugepage sizes (64k, 32M and 1G), the control files include:: @@ -40,11 +37,56 @@ files include:: hugetlb.1GB.max_usage_in_bytes hugetlb.1GB.usage_in_bytes hugetlb.1GB.failcnt + hugetlb.1GB.reservation_limit_in_bytes + hugetlb.1GB.reservation_max_usage_in_bytes + hugetlb.1GB.reservation_usage_in_bytes + hugetlb.1GB.reservation_failcnt hugetlb.64KB.limit_in_bytes hugetlb.64KB.max_usage_in_bytes hugetlb.64KB.usage_in_bytes hugetlb.64KB.failcnt + hugetlb.64KB.reservation_limit_in_bytes + hugetlb.64KB.reservation_max_usage_in_bytes + hugetlb.64KB.reservation_usage_in_bytes + hugetlb.64KB.reservation_failcnt hugetlb.32MB.limit_in_bytes hugetlb.32MB.max_usage_in_bytes hugetlb.32MB.usage_in_bytes hugetlb.32MB.failcnt + hugetlb.32MB.reservation_limit_in_bytes + hugetlb.32MB.reservation_max_usage_in_bytes + hugetlb.32MB.reservation_usage_in_bytes + hugetlb.32MB.reservation_failcnt + + +1. Reservation limits + +The HugeTLB controller allows to limit the HugeTLB reservations per control +group and enforces the controller limit at reservation time and at the fault of +hugetlb memory for which no reservation exists. Reservation limits +are superior to Page fault limits (see section 2), since Reservation limits are +enforced at reservation time (on mmap or shget), and never causes the +application to get SIGBUS signal if the memory was reserved before hand. For +MAP_NORESERVE allocations, the reservation limit behaves the same as the fault +limit, enforcing memory usage at fault time and causing the application to +receive a SIGBUS if it's crossing its limit. + +2. Page fault limits + +The HugeTLB controller allows to limit the HugeTLB usage (page fault) per +control group and enforces the controller limit during page fault. Since HugeTLB +doesn't support page reclaim, enforcing the limit at page fault time implies +that, the application will get SIGBUS signal if it tries to access HugeTLB +pages beyond its limit. This requires the application to know beforehand how +much HugeTLB pages it would require for its use. + + +3. Caveats with shared memory + +For shared hugetlb memory, both hugetlb reservation and page faults are charged +to the first task that causes the memory to be reserved or faulted, and all +subsequent uses of this reserved or faulted memory is done without charging. + +Shared hugetlb memory is only uncharged when it is unreserved or deallocated. +This is usually when the hugetlbfs file is deleted, and not when the task that +caused the reservation or fault has exited. -- 2.23.0.700.g56cf767bdb-goog