From patchwork Thu Jan 2 21:26:43 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dennis Zhou X-Patchwork-Id: 11316091 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 321E614B4 for ; Thu, 2 Jan 2020 21:27:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 10EBB21582 for ; Thu, 2 Jan 2020 21:27:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578000424; bh=Fwa49Pct4Oqcb4SSu0+lXaXOBf0B0dm0BQaXGpcsZUc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:In-Reply-To: References:List-ID:From; b=2czXJ2Sbhu+iLemPrQbCixMv/rC20BTjmhOjvl4vy1InrVb8vTSQe3wujiigurS/B iol5WKvH7gT/xAU0YiD2qQAUaq68dYEwJXd7b64pxd4/olDJ5RpqSAbkc0q67C79Ha IDE1qk2AHvbZWtghLNOyCVAOwmtW/KXO0JICiijs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726112AbgABV1D (ORCPT ); Thu, 2 Jan 2020 16:27:03 -0500 Received: from mail-qv1-f67.google.com ([209.85.219.67]:35376 "EHLO mail-qv1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726050AbgABV1C (ORCPT ); Thu, 2 Jan 2020 16:27:02 -0500 Received: by mail-qv1-f67.google.com with SMTP id u10so15438982qvi.2 for ; Thu, 02 Jan 2020 13:27:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=tg/k5+OeLFe7P1hVJ+bYqYqQSX6vUJvgrdOmMK11Ekw=; b=j9zX97bG+1/B+f3o/HYj0QFy9uitcTt0x6QRe+FTSUFVODYsF2/CPa3H++ObfDY2A+ VttOJDsfX8v+Dq9IbL5K+YLNkG0oF2AOnsmY8CfETtElMKO0W5Db478+niPH1gXFgPdj IwL1oo5IWOH5eNlkpt5rij7SiyJ+csixWZNQW/6IS4RgBJrIPZF5cWrkjnf4noA1Ihoy +jBbdmlVq40uCQ9nkvfsCpXV4O0NWveQANH9Ww7Ty9Z6rkhGjYLgAm07Yvodm/nXWfwm QvoZSXe9zt8n6AL3m0CQgehWZPCSPNROR1Byb2mDn+rI7VSa/J/kGtnXyQZmy4PM2lNX 9I7Q== X-Gm-Message-State: APjAAAUDkcw9rDPJ0YfzBBjvFA4VULNf+3RGPLpwJictTVrQyZsuxstO mpdKNirDtj05ZKyhItxFkDA= X-Google-Smtp-Source: APXvYqxcWp6WkVdLKrpkUnOEXcESIEDRPyVewIQ7cSCx4rmAeOLnOqA6eqsY5wJ7q6ab/Mry9NzbxQ== X-Received: by 2002:ad4:496f:: with SMTP id p15mr63101706qvy.191.1578000421147; Thu, 02 Jan 2020 13:27:01 -0800 (PST) Received: from dennisz-mbp.thefacebook.com ([163.114.130.128]) by smtp.gmail.com with ESMTPSA id f42sm17553933qta.0.2020.01.02.13.27.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 02 Jan 2020 13:27:00 -0800 (PST) From: Dennis Zhou To: David Sterba , Chris Mason , Josef Bacik , Omar Sandoval Cc: kernel-team@fb.com, linux-btrfs@vger.kernel.org, Dennis Zhou Subject: [PATCH 09/12] btrfs: increase the metadata allowance for the free_space_cache Date: Thu, 2 Jan 2020 16:26:43 -0500 Message-Id: <49f2d76f892a24fb6c9cd384f4c7ecc04e63522c.1577999991.git.dennis@kernel.org> X-Mailer: git-send-email 2.13.5 In-Reply-To: References: In-Reply-To: References: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Currently, there is no way for the free space cache to recover from being serviced by purely bitmaps because the extent threshold is set to 0 in recalculate_thresholds() when we surpass the metadata allowance. This adds a recovery mechanism by keeping large extents out of the bitmaps and increases the metadata upper bound to 64KB. The recovery mechanism bypasses this upper bound, thus making it a soft upper bound. But, with the bypass being 1MB or greater, it shouldn't add unbounded overhead. Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik --- fs/btrfs/free-space-cache.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index 8a4a3b9cd544..665f6eb6c828 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -24,7 +24,8 @@ #include "discard.h" #define BITS_PER_BITMAP (PAGE_SIZE * 8UL) -#define MAX_CACHE_BYTES_PER_GIG SZ_32K +#define MAX_CACHE_BYTES_PER_GIG SZ_64K +#define FORCE_EXTENT_THRESHOLD SZ_1M struct btrfs_trim_range { u64 start; @@ -1694,26 +1695,17 @@ static void recalculate_thresholds(struct btrfs_free_space_ctl *ctl) ASSERT(ctl->total_bitmaps <= max_bitmaps); /* - * The goal is to keep the total amount of memory used per 1gb of space - * at or below 32k, so we need to adjust how much memory we allow to be - * used by extent based free space tracking + * We are trying to keep the total amount of memory used per 1gb of + * space to be MAX_CACHE_BYTES_PER_GIG. However, with a reclamation + * mechanism of pulling extents >= FORCE_EXTENT_THRESHOLD out of + * bitmaps, we may end up using more memory than this. */ if (size < SZ_1G) max_bytes = MAX_CACHE_BYTES_PER_GIG; else max_bytes = MAX_CACHE_BYTES_PER_GIG * div_u64(size, SZ_1G); - /* - * we want to account for 1 more bitmap than what we have so we can make - * sure we don't go over our overall goal of MAX_CACHE_BYTES_PER_GIG as - * we add more bitmaps. - */ - bitmap_bytes = (ctl->total_bitmaps + 1) * ctl->unit; - - if (bitmap_bytes >= max_bytes) { - ctl->extents_thresh = 0; - return; - } + bitmap_bytes = ctl->total_bitmaps * ctl->unit; /* * we want the extent entry threshold to always be at most 1/2 the max @@ -2099,6 +2091,10 @@ static bool use_bitmap(struct btrfs_free_space_ctl *ctl, forced = true; #endif + /* This is a way to reclaim large regions from the bitmaps. */ + if (!forced && info->bytes >= FORCE_EXTENT_THRESHOLD) + return false; + /* * If we are below the extents threshold then we can add this as an * extent, and don't have to deal with the bitmap