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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 67F62C2B9F7 for ; Wed, 26 May 2021 09:38:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3D2606143C for ; Wed, 26 May 2021 09:38:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233240AbhEZJkR (ORCPT ); Wed, 26 May 2021 05:40:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233117AbhEZJkQ (ORCPT ); Wed, 26 May 2021 05:40:16 -0400 Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CC5FC061574 for ; Wed, 26 May 2021 02:38:45 -0700 (PDT) Received: by mail-ej1-x633.google.com with SMTP id c20so1400877ejm.3 for ; Wed, 26 May 2021 02:38:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ionos.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=lLHx+yN+NcA8pZ3fuZkAfmUPBqod1IBuoaflPXzNM/E=; b=PPEjYedCXI7Bqm3w6kXOOOAAFh1eeDIO+AjI3cYthI93VJGg09cZNZ3EcJSKvJmSVm twQJ4B4WQwRTp4GHEyj0+9lCGc1Yu/yI20E+2RTHdxFJu9W5cqPrO8q1mHSRxTM8rwsA XBsj4X6B9ajUUHuoCaLpMqAbQteme9eWI+X9l0OPTsCd1kRSzhLG+6YnwNTxiwgdD6FC DAYjScMDQ2b73jsQokSuw5WWDerK1Irhr2NEhWsp84Ql0vSlrP32RJCNL8MRDOlOE0Y3 cKUT6knrksiYCGGzfMAPrMHzzygUBsdoaaRVLYJ1NU0JdvXwM7CphgujFPcNc2aAzTci By/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=lLHx+yN+NcA8pZ3fuZkAfmUPBqod1IBuoaflPXzNM/E=; b=Ig08fjxxdzSyj/3psEYN05xD7dsQhQ0FGMX9D084n2G3pJ46//z9iYtuFW+JI9ny59 8v5+JCkukIQzjTq5dZmjnHzfQymK9YJCgB0eqwB9zU9yiRRgzNaRatxwAWZ1XUqfMpNw ajijSZnLx1yrw8aBzQSVm+E+WJ9dA2jJtlBjSPARMUmzkeSGMyLB+PqGJTJlRVHUfpOR GPfwYygJZKr2c+9JlI0jCeC9w8wtOFplb8ZnFjLQ2Fjzgu7hNOmamDtmjVNWzJH+bM2t IH9J/cmuvaZGHwJlau0RLwZd/fMkMA1URUWn1Z9gwWyqnvS1g2MgijdonX/yWAl1jr2z N4bQ== X-Gm-Message-State: AOAM533JHZVqcY6yPunfnoL97tzX3tFeCfEZtfbhHIR6SnittCbsUOdw VmmgVpEwjUmMiv9KLRN4suH0XYv15Oh0AAqxC1stoQ== X-Google-Smtp-Source: ABdhPJxkpsb2bRs2xgoezQJDNgzeYqz7QEf8+P6BWkZhYbT7fkBk5NsuIOtIg/E7rilH1pQrLuhl6656MCO3TpylFPg= X-Received: by 2002:a17:906:ccde:: with SMTP id ot30mr33718349ejb.353.1622021924092; Wed, 26 May 2021 02:38:44 -0700 (PDT) MIME-Version: 1.0 References: <20210517091844.260810-1-gi-oh.kim@ionos.com> <20210517091844.260810-14-gi-oh.kim@ionos.com> <20210525201543.GA3482418@nvidia.com> In-Reply-To: From: Jinpu Wang Date: Wed, 26 May 2021 11:38:33 +0200 Message-ID: Subject: Re: [PATCHv2 for-next 13/19] RDMA/rtrs-srv: Replace atomic_t with percpu_ref for ids_inflight To: Haris Iqbal Cc: Jason Gunthorpe , Gioh Kim , RDMA mailing list , Bart Van Assche , Leon Romanovsky , Doug Ledford , Md Haris Iqbal Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Wed, May 26, 2021 at 11:17 AM Haris Iqbal wrote: > > On Tue, May 25, 2021 at 10:15 PM Jason Gunthorpe wrote: > > > > On Mon, May 17, 2021 at 11:18:37AM +0200, Gioh Kim wrote: > > > From: Md Haris Iqbal > > > > > > ids_inflight is used to track the inflight IOs. But the use of atomic_t > > > variable can cause performance drops and can also become a performance > > > bottleneck. > > > > > > This commit replaces the use of atomic_t with a percpu_ref structure. The > > > advantage it offers is, it doesn't check if the reference has fallen to 0, > > > until the user explicitly signals it to; and that is done by the > > > percpu_ref_kill() function call. After that, the percpu_ref structure > > > behaves like an atomic_t and for every put call, checks whether the > > > reference has fallen to 0 or not. > > > > > > rtrs_srv_stats_rdma_to_str shows the count of ids_inflight as 0 > > > for user-mode tools not to be confused. > > > > > > Fixes: 9cb837480424e ("RDMA/rtrs: server: main functionality") > > > Signed-off-by: Md Haris Iqbal > > > Signed-off-by: Jack Wang > > > Signed-off-by: Gioh Kim > > > --- > > > drivers/infiniband/ulp/rtrs/rtrs-srv-stats.c | 12 +++--- > > > drivers/infiniband/ulp/rtrs/rtrs-srv.c | 43 +++++++++++++------- > > > drivers/infiniband/ulp/rtrs/rtrs-srv.h | 4 +- > > > 3 files changed, 35 insertions(+), 24 deletions(-) > > > > > > diff --git a/drivers/infiniband/ulp/rtrs/rtrs-srv-stats.c b/drivers/infiniband/ulp/rtrs/rtrs-srv-stats.c > > > index e102b1368d0c..df1d7d6b1884 100644 > > > --- a/drivers/infiniband/ulp/rtrs/rtrs-srv-stats.c > > > +++ b/drivers/infiniband/ulp/rtrs/rtrs-srv-stats.c > > > @@ -27,12 +27,10 @@ ssize_t rtrs_srv_stats_rdma_to_str(struct rtrs_srv_stats *stats, > > > char *page, size_t len) > > > { > > > struct rtrs_srv_stats_rdma_stats *r = &stats->rdma_stats; > > > - struct rtrs_srv_sess *sess = stats->sess; > > > > > > - return scnprintf(page, len, "%lld %lld %lld %lld %u\n", > > > - (s64)atomic64_read(&r->dir[READ].cnt), > > > - (s64)atomic64_read(&r->dir[READ].size_total), > > > - (s64)atomic64_read(&r->dir[WRITE].cnt), > > > - (s64)atomic64_read(&r->dir[WRITE].size_total), > > > - atomic_read(&sess->ids_inflight)); > > > + return sysfs_emit(page, "%lld %lld %lld %lldn\n", > > > + (s64)atomic64_read(&r->dir[READ].cnt), > > > + (s64)atomic64_read(&r->dir[READ].size_total), > > > + (s64)atomic64_read(&r->dir[WRITE].cnt), > > > + (s64)atomic64_read(&r->dir[WRITE].size_total)); > > > } > > > > This seems like an unrelated hunk > > Previous to the commit, ids_inflight was an atomic variable, and hence > was read and printed along with other rtrs_srv stats. With this > commit, since ids_inflight is changed to percpu_ref, we removed it > being printed in rtrs_srv stats. Its related to the commit. I think Jason meant the sysfs_emit conversion should be in a separate patch. > > > > > > Jason