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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 B8346C43381 for ; Thu, 18 Feb 2021 16:35:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C80B64DFF for ; Thu, 18 Feb 2021 16:35:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233496AbhBRQev (ORCPT ); Thu, 18 Feb 2021 11:34:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:59058 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231392AbhBRNta (ORCPT ); Thu, 18 Feb 2021 08:49:30 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5710864E76; Thu, 18 Feb 2021 13:48:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1613656117; bh=m9n2RWGKyH7DlKz/4HUd/rwoeOVJIoj7rqtYKwqAeBs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nozJmFDBjdsISqTrAWTu99Lt0fXxbMA7mcqQJ/KOBAdcQyC9RVA4EPErgBTIDRdS6 82yx5KZXgHueCekkKb3bSNzj2KaxyMVK9fp0ZvIUIbL9RvSTngi9W7/cLjcNiHwT3C 52PLUaLmWzmqvZ082S5OCcH82TwUTY+dVEGwi0L0= Date: Thu, 18 Feb 2021 14:48:34 +0100 From: Greg KH To: Avri Altman Cc: "James E . J . Bottomley" , "Martin K . Petersen" , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Bart Van Assche , yongmyung lee , Daejun Park , alim.akhtar@samsung.com, asutoshd@codeaurora.org, Zang Leigang , Avi Shchislowski , Bean Huo , cang@codeaurora.org, stanley.chu@mediatek.com Subject: Re: [PATCH v3 9/9] scsi: ufshpb: Make host mode parameters configurable Message-ID: References: <20210218131932.106997-1-avri.altman@wdc.com> <20210218131932.106997-10-avri.altman@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210218131932.106997-10-avri.altman@wdc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 18, 2021 at 03:19:32PM +0200, Avri Altman wrote: > We can make use of this commit, to elaborate some more of the host > control mode logic, explaining what role play each and every variable. > > While at it, allow those parameters to be configurable. > > Signed-off-by: Avri Altman > --- > Documentation/ABI/testing/sysfs-driver-ufs | 68 ++++++ > drivers/scsi/ufs/ufshpb.c | 254 +++++++++++++++++++-- > drivers/scsi/ufs/ufshpb.h | 18 ++ > 3 files changed, 326 insertions(+), 14 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-driver-ufs b/Documentation/ABI/testing/sysfs-driver-ufs > index 0017eaf89cbe..1d72201c4953 100644 > --- a/Documentation/ABI/testing/sysfs-driver-ufs > +++ b/Documentation/ABI/testing/sysfs-driver-ufs > @@ -1322,3 +1322,71 @@ Description: This entry shows the maximum HPB data size for using single HPB > === ======== > > The file is read only. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/activation_thld > +Date: February 2021 > +Contact: Avri Altman > +Description: In host control mode, reads are the major source of activation > + trials. once this threshold hs met, the region is added to the > + "to-be-activated" list. Since we reset the read counter upon > + write, this include sending a rb command updating the region > + ppn as well. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/normalization_factor > +Date: February 2021 > +Contact: Avri Altman > +Description: In host control mode, We think of the regions as "buckets". > + Those buckets are being filled with reads, and emptied on write. > + We use entries_per_srgn - the amount of blocks in a subregion as > + our bucket size. This applies because HPB1.0 only concern a > + single-block reads. Once the bucket size is crossed, we trigger > + a normalization work - not only to avoid overflow, but mainly > + because we want to keep those counters normalized, as we are > + using those reads as a comparative score, to make various decisions. > + The normalization is dividing (shift right) the read counter by > + the normalization_factor. If during consecutive normalizations > + an active region has exhaust its reads - inactivate it. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/eviction_thld_enter > +Date: February 2021 > +Contact: Avri Altman > +Description: Region deactivation is often due to the fact that eviction took > + place: a region become active on the expense of another. This is > + happening when the max-active-regions limit has crossed. > + In host mode, eviction is considered an extreme measure. We > + want to verify that the entering region has enough reads, and > + the exiting region has much less reads. eviction_thld_enter is > + the min reads that a region must have in order to be considered > + as a candidate to evict other region. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/eviction_thld_exit > +Date: February 2021 > +Contact: Avri Altman > +Description: same as above for the exiting region. A region is consider to > + be a candidate to be evicted, only if it has less reads than > + eviction_thld_exit. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/read_timeout_ms > +Date: February 2021 > +Contact: Avri Altman > +Description: In order not to hang on to “cold” regions, we shall inactivate > + a region that has no READ access for a predefined amount of > + time - read_timeout_ms. If read_timeout_ms has expired, and the > + region is dirty - it is less likely that we can make any use of > + HPB-READing it. So we inactivate it. Still, deactivation has > + its overhead, and we may still benefit from HPB-READing this > + region if it is clean - see read_timeout_expiries. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/read_timeout_expiries > +Date: February 2021 > +Contact: Avri Altman > +Description: if the region read timeout has expired, but the region is clean, > + just re-wind its timer for another spin. Do that as long as it > + is clean and did not exhaust its read_timeout_expiries threshold. > + > +What: /sys/class/scsi_device/*/device/hpb_param_sysfs/timeout_polling_interval_ms > +Date: February 2021 > +Contact: Avri Altman > +Description: the frequency in which the delayed worker that checks the > + read_timeouts is awaken. > +>>>>>>> ef6bf08e666d... scsi: ufshpb: Make host mode parameters configurable Did you mean for this last line to be here?