From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f179.google.com (mail-il1-f179.google.com [209.85.166.179]) (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 45DE635962 for ; Wed, 16 Apr 2025 15:07:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744816042; cv=none; b=MuAIg0OsCh9u3nhjs0YegUDJ/w0JBTYk5ub/8DOUrAMekX+2kITxrdfCj5h40NVP0yIGWdrQT71TjZCCFaUTeoLywoq1X1AQIkf8KVArh5rL+K3eULoimk0bReeRsl3gqot/Tf1eROY6bx/BfkviFELrcqFVm9fuSfXXCAGwXsY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744816042; c=relaxed/simple; bh=xydEv1bJS8nBM6VoPoPvUsURJKyB/Zca26umfk5kWjM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EdqCYXMPbH6Ec096CMJ5QIDn+Ki4k2bGIkh61OFtavKJXXYFevcltgd/Z5aibmntRPELBdnRrP4xKxPnJAElU/xD1CW2LqyjrK6P0HtzRdoxY7pSoGEcG3PRvoBnVaaIAhAgFd+vvKwIfeEKts2KPk6HPNdLtt3e0mVUwaUIm+4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=luvrRmTW; arc=none smtp.client-ip=209.85.166.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="luvrRmTW" Received: by mail-il1-f179.google.com with SMTP id e9e14a558f8ab-3d6d162e516so52446705ab.1 for ; Wed, 16 Apr 2025 08:07:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1744816038; x=1745420838; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=uSiz4ta79sjKF4kdwzdjhicKXhB4rJNdion/ll08cgM=; b=luvrRmTW1ax0ITztpQatJNCGdU8WMDFJkKEIQPpXA5kWbTyOtMA6lX1Obb3BacsCbm Tlkj+co6su9D3PWSiKvzkdIIrbPtCoVlEqM7N2X26nbr1RgvM3/OhTT/NpyIavuPZL2k /DSaeVYc8NDx9HcwSFCYoiYDMkWBkRbUtTL+z5RJvzDWrJJ9qJA5JskvkJ9WG2PtIdj+ 4BEzXeBOSsbU+zdHoYBLWSX59W3qMesue4hjOX9yjjgjs+4awHdAxNgXOXR2bdvDUuAr 1vem8v1HCqVKT0pO0AQD6k3qQGQ9q9zdYXwnmFaL4jwJ8a7ULmJ7kqkx5lXKZ4CZ3qB8 3vGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1744816038; x=1745420838; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=uSiz4ta79sjKF4kdwzdjhicKXhB4rJNdion/ll08cgM=; b=DpueH2yTJXyOPAavcdlbQdltWS9QiTMm+VBlo9ad8+PAAPy4V4hxHSAJRxkrGUoViM O2Cx+BJxxYflm+afnWgh+WUESCYj/YkYGk6U1kKDrc2LB3Lve1o+Owk4FCHaJOO57GTe FkHzo6AABADASUmreT/uCzOVHS7g517XMKae5YqSItyoLPBhrHkVyVuhlaZURABNUBE7 rgzViLz4GUlIZXNm+1oB1In5aXHAtDnAAfI4Wy7mKgTt7Hy3Rpg6F/ZkBmCvdT+0eXC4 eYNoxs1ZuIE1OouBeKLyIXEv2pulfPZYFLOAPL4DqTTpsPA5K1psGuQMnMm7l7z3A+1N sreA== X-Forwarded-Encrypted: i=1; AJvYcCUMQt1pT0mKR8CRnntc9bpjlgjUfKg+v1MxD6IfA+Xjo8o2qRNQTmV1MpzVinPVSB+y+2tEqJZP2A==@vger.kernel.org X-Gm-Message-State: AOJu0YxXZmtCbj9+hv+lXbKf0iKAQI1+S3ZKlfKGpmA0E5bP1fw8dB7y M1RkHroFKz5ELrw8O0YAiuJE06dpBlZF5dT4zXqZ8tGR9JLr1fJcihjYzhCW2GM= X-Gm-Gg: ASbGncv+hBuCvdHg0K+wSjfgAXPNomNhMJTubu2YdO9KDdE3ykjWC0nQswoQIEcZZ8O gaUC03X83FcY/v/yOUcQK/CQfCvggT6vARYs/I9JEhwP8UU/e7t4Min23pp+qdXGPhvcUmvmhKJ I0fiGQq1JWsoIVXSWoEWTPDWCj5aQ/X+uoT+xw/j0TSKpOBoZYP1Q8htTptJVZ0oCJmkGq9+FF7 GIEMZz7NqRVSSZ/fgKIy+UkC0APg21pyi9vw++Hk/Z+w2gKU1pifUr7yWZevRFZ6URamwpBKbj8 7DtdyPdll5H1x6I4eQrVUR0NGZxMPDdxJEZJjTenyZFeo6A= X-Google-Smtp-Source: AGHT+IEiQF0hJJBv4FKHVHSG0TYD0Ys3nz+ZNjCcYIevxZBop88KC6KOO3PSA/ty3Te7NQIFJkQtZw== X-Received: by 2002:a05:6e02:216b:b0:3d6:d162:be54 with SMTP id e9e14a558f8ab-3d815b5e1dfmr19479345ab.14.1744816038264; Wed, 16 Apr 2025 08:07:18 -0700 (PDT) Received: from [192.168.1.116] ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id 8926c6da1cb9f-4f505e01512sm3601391173.102.2025.04.16.08.07.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Apr 2025 08:07:17 -0700 (PDT) Message-ID: <37c982b5-92e1-4253-b8ac-d446a9a7d932@kernel.dk> Date: Wed, 16 Apr 2025 09:07:17 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] io_uring/rsrc: send exact nr_segs for fixed buffer To: Pavel Begunkov , Nitesh Shetty Cc: gost.dev@samsung.com, nitheshshetty@gmail.com, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250416054413.10431-1-nj.shetty@samsung.com> <98f08b07-c8de-4489-9686-241c0aab6acc@gmail.com> Content-Language: en-US From: Jens Axboe In-Reply-To: <98f08b07-c8de-4489-9686-241c0aab6acc@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/16/25 9:03 AM, Pavel Begunkov wrote: > On 4/16/25 06:44, Nitesh Shetty wrote: >> Sending exact nr_segs, avoids bio split check and processing in >> block layer, which takes around 5%[1] of overall CPU utilization. >> >> In our setup, we see overall improvement of IOPS from 7.15M to 7.65M [2] >> and 5% less CPU utilization. >> >> [1] >> 3.52% io_uring [kernel.kallsyms] [k] bio_split_rw_at >> 1.42% io_uring [kernel.kallsyms] [k] bio_split_rw >> 0.62% io_uring [kernel.kallsyms] [k] bio_submit_split >> >> [2] >> sudo taskset -c 0,1 ./t/io_uring -b512 -d128 -c32 -s32 -p1 -F1 -B1 -n2 >> -r4 /dev/nvme0n1 /dev/nvme1n1 >> >> Signed-off-by: Nitesh Shetty >> --- >> io_uring/rsrc.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c >> index b36c8825550e..6fd3a4a85a9c 100644 >> --- a/io_uring/rsrc.c >> +++ b/io_uring/rsrc.c >> @@ -1096,6 +1096,9 @@ static int io_import_fixed(int ddir, struct iov_iter *iter, >> iter->iov_offset = offset & ((1UL << imu->folio_shift) - 1); >> } >> } >> + iter->nr_segs = (iter->bvec->bv_offset + iter->iov_offset + >> + iter->count + ((1UL << imu->folio_shift) - 1)) / >> + (1UL << imu->folio_shift); > > That's not going to work with ->is_kbuf as the segments are not uniform in > size. Oops yes good point. > And can we make it saner? Split it into several statements, add variables > for folio size and so, or maybe just use ALIGN. If moved above, you > probably don't even need to recalc > > iter->bvec->bv_offset + iter->iov_offset Agree, was trying to do that with the shift at least, but seems like there is indeed room for further improvements here in terms of readability. -- Jens Axboe