From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f180.google.com (mail-pf1-f180.google.com [209.85.210.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 87C9F3771F; Sun, 21 Jan 2024 15:37:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705851425; cv=none; b=g136HdmKrKhwih3yT2cuEJv4ACBG9eDxwgWEdWXVjEhJP3Th6NKc7sNk4fOGwjD+Og8YhMV2TvDASOivdi98fUyXKUqP3WpRcPOj0QM3ybjluIjNGkiFrPYMgffljEDCNXkLVWeJirqV6idpOGAdBe9sdK5+ohQ84gLGKOJN+VM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705851425; c=relaxed/simple; bh=td7eYq5RRdZjgP7IOM9O5bSI3K4VazA2jQDoOaruLEY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=lr8wtKlkoBRQR7rjvjrcSHLBVaqCznk8ECnXgImJ1hBfpD05Cm/S2HJIa9QUqWwiEIZvtuFktSEssvubqnt9vDV7+37NjEk/BoCayBjdox6nInu8iDyfPvLrO3L9u+A7gRFYzeYSGyk17Fy4/Hqkw2TSDfqaPqyDpERU7oKtlLw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=F/uylxvv; arc=none smtp.client-ip=209.85.210.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="F/uylxvv" Received: by mail-pf1-f180.google.com with SMTP id d2e1a72fcca58-6d9b41a3cb7so828814b3a.0; Sun, 21 Jan 2024 07:37:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1705851424; x=1706456224; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=2pqHvvCphlALlajToOUOu8ABe7Bhki2MXmZlVOF4qBQ=; b=F/uylxvvWe45LqSORYN5ugmKL87jo+XNva6oXhtSANRpkM5TDGds2oAcUG5Ifa1P8a N8qZNUEZ4XG+FTo8srme4S9gcBHBGhDMb06F3wTk4tts5+HLQ26/bweMC5soMwABPDLP 4IVCxBnYcQtnkQLOoUnUQbMqUuJM6G4NOVwArSxHw55WdNjsj3Wq+DfB/3aUoZ40XVBw NYysfNSdTQPLVHzijOmMTw4MxCS9sIsrugHqpwkMPjhC+oKWNUyS8OojSqjbzlNrqbU6 3Q8wljLamC/soitqdk2h22wBcP0yC0tnzQvYildMNULop9qUZHU0gSputMlkRtrbaA4K TZkA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705851424; x=1706456224; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=2pqHvvCphlALlajToOUOu8ABe7Bhki2MXmZlVOF4qBQ=; b=dvCPvYuHyKNvQTUsRhVIC4lFNFTaHWi/HwFQ1aRDujbKJ1EIDWjCj4YJ2C5XdtJeVD FPtp20wXhu9oY8H6myI8d68yP+oxsMrT1lXAf4MDVjcHvGCL8EN67bRuu1Pcba5FHXL8 pY/FhwYJ13mU5tDnbOkmJb5PKhkBf/gm5VjlziFrXqnHsF5+1LyRSN/4qMRNFqIN9J8c 4wCFpMIkHeOlvgl+OxMEanLpmwy0ZOboyTrvd6k6E4Q1wVb6KALs63qvu7h22pBtR3l3 r6DJvveZ8FaqkHhgPW4nnjbJhhGV5KjzSx0TcA2JuMN4Hgt40wBZYrdOgRPdhTyma8lN QNjg== X-Gm-Message-State: AOJu0YzAzHVQN0uViyhOO8RLZygQO7LCEwdEU3QrzFSbObkTs870a0b5 yaNKVolek/BtOlwjfTd3J+DRoruea49EnZFcADUBgLgugNWTSKhi X-Google-Smtp-Source: AGHT+IG+D6at0+cAHIsJd/0BlRcS+2PEbB1TO9MOrWa17WDiILOJxIBA0dyciguF6FOdTC2vq+MDJg== X-Received: by 2002:a17:90a:c286:b0:290:19c1:103f with SMTP id f6-20020a17090ac28600b0029019c1103fmr3578520pjt.1.1705851423879; Sun, 21 Jan 2024 07:37:03 -0800 (PST) Received: from localhost.localdomain ([140.116.154.65]) by smtp.gmail.com with ESMTPSA id sv13-20020a17090b538d00b0028d8fa0171asm7744347pjb.35.2024.01.21.07.37.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 21 Jan 2024 07:37:03 -0800 (PST) From: Kuan-Wei Chiu To: colyli@suse.de, kent.overstreet@linux.dev Cc: bfoster@redhat.com, jserv@ccns.ncku.edu.tw, linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org, linux-bcachefs@vger.kernel.org, Kuan-Wei Chiu Subject: [PATCH 2/5] bcachefs: Introduce parent function for sort_cmp_size() Date: Sun, 21 Jan 2024 23:36:46 +0800 Message-Id: <20240121153649.2733274-3-visitorckw@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240121153649.2733274-1-visitorckw@gmail.com> References: <20240121153649.2733274-1-visitorckw@gmail.com> Precedence: bulk X-Mailing-List: linux-bcache@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When dealing with array indices, the parent's index can be obtained using the formula (i - 1) / 2. However, when working with byte offsets, this approach is not straightforward. To address this, we have introduced a branch-free parent function that does not require any division operations to calculate the parent's byte offset. Signed-off-by: Kuan-Wei Chiu --- This patch has undergone unit testing using the following code [1]. [1]: static int test(void) { size_t i, p, size, lsbit; for (i = 0; i < 10000; i++) { size = get_random_u32() % (1U << 10); lsbit = size & -size; i = get_random_u32() % (1U << 20) * size + size; p = parent(i, lsbit, size); if (p != (i / size - 1) / 2 * size) return -1; } return 0; } fs/bcachefs/util.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/bcachefs/util.c b/fs/bcachefs/util.c index bbc83b43162e..f5bbf96df2ce 100644 --- a/fs/bcachefs/util.c +++ b/fs/bcachefs/util.c @@ -907,6 +907,13 @@ static inline void do_swap(void *base, size_t n, size_t size, size); } +static inline size_t parent(size_t i, size_t lsbit, size_t size) +{ + i -= size; + i -= size & -(i & lsbit); + return i >> 1; +} + void eytzinger0_sort(void *base, size_t n, size_t size, int (*cmp_func)(const void *, const void *, size_t), void (*swap_func)(void *, void *, size_t)) -- 2.25.1