From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0A60A3F823C; Wed, 8 Jul 2026 09:06:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783501602; cv=none; b=MGJXqYVh1bV6alFxvarQZA5c2phiz+q8wJ12VgRQEV+in7Ke19wyNxm9B14f/cDPUX/fqqxajoO5oVuyPrGQV8oznF9/1yuGf9pSwOMOx+6gxTwWaHDfiJvntufnA+ahbJDxWWlvtL0h09Yh4EFykeiuCagdW1L70LNCyYflnKU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783501602; c=relaxed/simple; bh=NmIqwbSwTpB5DAYZsyHpyJq6B5woSevVMVnLWHQQYE8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NhL0cJmHjR9liZwA8LJCKiwxrRBwIdVlGAK0w6w7DJKCFMN2pm/5DNz8YxmY0q3sRbf60ph1769dlXBuE03yquuw3B8xQWUUax+helHmcvYNtI4sg5sr2XcOGtaJfMUHzAwXvJG+yoFcaXQhkxI/yx/ZAlM+2lZ58HMqZBDvGaE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=lst.de; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=Qq8qqhhe; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Qq8qqhhe" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=x1zj+g8oFCvReKwlDRL92FlooeEtsGPAF0K/QyY6e18=; b=Qq8qqhheAJI4fcRdFaTMT6oQ9c l8K6QnvNqUDFBD4w+IHVnzu3EywhbEMp/3j3EwsozyAilkgTYGJ7yjteuG7fSTnUYp0w0zPBZ3yab 9hI4y4bAkFKERZC8HH6GXpnOZRuySVBJKHcKiXT+I2LtkjEAm1Z5suTsFc5aMD0Ui6QYSR1STxY37 O0cvoGF6G3EhXoDt0n2NL7SCs9dRp+jjNTbhwAeblLCyQ9KEsRDlM+W4P0N902W2WVvbwTiFOsC8N G7NzU5ccFQhMnrtr3n82dwXJt0SrReRi6u/f0fAa13HM67xsX6nTh5BH52NJlODTbdzgbO1Bjyb2F F0nvzxQg==; Received: from 213-147-165-125.nat.highway.webapn.at ([213.147.165.125] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1whOEp-0000000Ghwf-2fWk; Wed, 08 Jul 2026 09:06:40 +0000 From: Christoph Hellwig To: Andrew Morton Cc: Eric Biggers , linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/8] xor: improve the runtime selection benchmark Date: Wed, 8 Jul 2026 11:05:16 +0200 Message-ID: <20260708090614.1431014-3-hch@lst.de> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260708090614.1431014-1-hch@lst.de> References: <20260708090614.1431014-1-hch@lst.de> Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Use plain ktime_get_ns for the timing, use 4 + 1 disks for a realistic load, and report the throughput on the data disks instead of the that on the parity disk, which isn't all that useful. Signed-off-by: Christoph Hellwig --- lib/raid/xor/xor-core.c | 55 +++++++++++++++++++---------------------- 1 file changed, 26 insertions(+), 29 deletions(-) diff --git a/lib/raid/xor/xor-core.c b/lib/raid/xor/xor-core.c index 50931fbf0324..a890cec21bbc 100644 --- a/lib/raid/xor/xor-core.c +++ b/lib/raid/xor/xor-core.c @@ -10,7 +10,6 @@ #include #include #include -#include #include #include #include "xor_impl.h" @@ -73,59 +72,56 @@ void __init xor_force(struct xor_block_template *tmpl) forced_template = tmpl; } -#define BENCH_SIZE 4096 +#define BENCH_SIZE SZ_4K +#define NR_SRCS 4 #define REPS 800U -static void __init -do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) +static void __init do_xor_speed(struct xor_block_template *tmpl, void *dest, + void *srcs[NR_SRCS]) { - int speed; - unsigned long reps; - ktime_t min, start, t0; - void *srcs[1] = { b2 }; + u64 t; + int i; preempt_disable(); - - reps = 0; - t0 = ktime_get(); - /* delay start until time has advanced */ - while ((start = ktime_get()) == t0) - cpu_relax(); - do { + t = ktime_get_ns(); + for (i = 0; i < REPS; i++) { mb(); /* prevent loop optimization */ - tmpl->xor_gen(b1, srcs, 1, BENCH_SIZE); + tmpl->xor_gen(dest, srcs, NR_SRCS, BENCH_SIZE); mb(); - } while (reps++ < REPS || (t0 = ktime_get()) == start); - min = ktime_sub(t0, start); - + } + t = ktime_get_ns() - t; preempt_enable(); - // bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s] - speed = (1000 * reps * BENCH_SIZE) / (unsigned int)ktime_to_ns(min); - tmpl->speed = speed; + /* bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s] */ + tmpl->speed = div64_u64((u64)BENCH_SIZE * REPS * NR_SRCS * 1000, t); - pr_info(" %-16s: %5d MB/sec\n", tmpl->name, speed); + pr_info(" %-16s: %5d MB/sec\n", tmpl->name, tmpl->speed); } static int __init calibrate_xor_blocks(void) { - void *b1, *b2; struct xor_block_template *f, *fastest; + void *srcs[NR_SRCS]; + void *buf, *dest; + int i; if (forced_template) return 0; - b1 = kmalloc(PAGE_SIZE * 4, GFP_KERNEL); - if (!b1) { + buf = kmalloc(BENCH_SIZE * (NR_SRCS + 1), GFP_KERNEL); + if (!buf) { pr_warn("xor: Yikes! No memory available.\n"); return -ENOMEM; } - b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; + get_random_bytes(buf, BENCH_SIZE * (NR_SRCS + 1)); + dest = buf; + for (i = 0; i < NR_SRCS; i++) + srcs[i] = buf + (i + 1) * BENCH_SIZE; pr_info("xor: measuring software checksum speed\n"); fastest = template_list; for (f = template_list; f; f = f->next) { - do_xor_speed(f, b1, b2); + do_xor_speed(f, dest, srcs); if (f->speed > fastest->speed) fastest = f; } @@ -133,9 +129,10 @@ static int __init calibrate_xor_blocks(void) pr_info("xor: using function: %s (%d MB/sec)\n", fastest->name, fastest->speed); - kfree(b1); + kfree(buf); return 0; } +#undef NR_SRCS #ifdef CONFIG_XOR_BLOCKS_ARCH #include "xor_arch.h" /* $SRCARCH/xor_arch.h */ -- 2.53.0