From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 011.lax.mailroute.net (011.lax.mailroute.net [199.89.1.14]) (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 DC9993D7D67 for ; Thu, 2 Apr 2026 17:14:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775150074; cv=none; b=jQlwqj9F0QnSID2LmoSRTbzct3klcBqdgYFAVELe91dQ2YTsFLSWiXqlrPfgbmJk9fmPTMnBghvKHOJ4sefCPm5mg8Scr1AgyqrR9OWqq5NTO5j1VtID4w08v0UJC3Jrr6QozJofOw2958lbOXGyO8LsCaAOGzb3dKomYGisF+8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775150074; c=relaxed/simple; bh=aBg0kVG3+WCOuu+gX8HAdyE4pt30MMUuHlRDgHlBV0k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=emaKwYkS9mrxoslO6gmQeWoiTByUDEn8CHYLYsAM+Ng9wBhw5hiaGEMrbUFEO72ARFrKNDhX3sKv/fcFwSUvfrSvfctufjrmem2OXNZjB+miTxHIc3wwxNlsTEY+YRuOXOm/vG4lY3+Uwy1oXiJuDaCG9CPSEQF5i3Tt6aMcQes= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=tp/JeVbW; arc=none smtp.client-ip=199.89.1.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="tp/JeVbW" Received: from localhost (localhost [127.0.0.1]) by 011.lax.mailroute.net (Postfix) with ESMTP id 4fmpPH5d8Pz1XM6Jc; Thu, 2 Apr 2026 17:14:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:mime-version:references:in-reply-to :x-mailer:message-id:date:date:subject:subject:from:from :received:received; s=mr01; t=1775150063; x=1777742064; bh=zSOQD 9pRWNA1gh0mwO3uk3uOqFI0A7+9pUeJ0RRwuVI=; b=tp/JeVbWCHw4QE32MWc+A Iish3lPqbGYpu3BY9Eg8qu7/axf/kB1DvVSz94BlDPUjgagGlHGyYFIjm5O6ln4J pZwmbW0QrsUwPfLJzbM6ofN6ilRRImBYPc1VG9fB3BzWELppkRVJRxK3U6rNjX24 yf0nzx3/xK3immOR2saOox0f/900BElLfbUUZgFOXsbka/w0Vh0PqsgUAUq+Qmpl dZBy2CNN2g1OgradHo4DrcQ4iJrKF3Ij27Q5FSP814niDRIzjQNksQPjlqbBrNlr u+bJsR//tG4c3dRoIkPgaOCt1RUmwfxIv2QydRZJjfr0kAq87diwMTFkLRTaa5Dh g== X-Virus-Scanned: by MailRoute Received: from 011.lax.mailroute.net ([127.0.0.1]) by localhost (011.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id 90ezATQjw04P; Thu, 2 Apr 2026 17:14:23 +0000 (UTC) Received: from bvanassche.mtv.corp.google.com (unknown [104.135.180.219]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 011.lax.mailroute.net (Postfix) with ESMTPSA id 4fmpPB1s2Rz1XM6Jb; Thu, 2 Apr 2026 17:14:21 +0000 (UTC) From: Bart Van Assche To: "Martin K . Petersen" Cc: linux-scsi@vger.kernel.org, Bart Van Assche , Manivannan Sadhasivam , "James E.J. Bottomley" Subject: [PATCH v2 2/2] ufs: qcom: Reduce interrupt latency Date: Thu, 2 Apr 2026 10:14:02 -0700 Message-ID: <20260402171404.3008494-3-bvanassche@acm.org> X-Mailer: git-send-email 2.53.0.1213.gd9a14994de-goog In-Reply-To: <20260402171404.3008494-1-bvanassche@acm.org> References: <20260402171404.3008494-1-bvanassche@acm.org> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Defer completion processing to thread context on slower CPU cores to prevent interrupt latency spikes. On the fastest CPU cores, keep processing all completions in interrupt context. Signed-off-by: Bart Van Assche --- drivers/ufs/host/ufs-qcom.c | 33 +++++++++++++++++++++++++++++---- 1 file changed, 29 insertions(+), 4 deletions(-) diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c index 5a58ffef3d27..4aabbd14631e 100644 --- a/drivers/ufs/host/ufs-qcom.c +++ b/drivers/ufs/host/ufs-qcom.c @@ -2370,6 +2370,16 @@ struct ufs_qcom_irq { struct ufs_hba *hba; }; =20 +static irqreturn_t ufs_qcom_mcq_threaded_esi_handler(int irq, void *data= ) +{ + struct ufs_qcom_irq *qi =3D data; + struct ufs_hba *hba =3D qi->hba; + + ufshcd_mcq_poll_cqe_lock(hba, &hba->uhq[qi->idx]); + + return IRQ_HANDLED; +} + static irqreturn_t ufs_qcom_mcq_esi_handler(int irq, void *data) { struct ufs_qcom_irq *qi =3D data; @@ -2377,9 +2387,22 @@ static irqreturn_t ufs_qcom_mcq_esi_handler(int ir= q, void *data) struct ufs_hw_queue *hwq =3D &hba->uhq[qi->idx]; =20 ufshcd_mcq_write_cqis(hba, 0x1, qi->idx); - ufshcd_mcq_poll_cqe_lock(hba, hwq); =20 - return IRQ_HANDLED; + if (arch_scale_cpu_capacity(raw_smp_processor_id()) =3D=3D + SCHED_CAPACITY_SCALE) { + ufshcd_mcq_poll_cqe_lock(hba, hwq); + return IRQ_HANDLED; + } + + if (ufshcd_mcq_poll_n_cqe_lock(hba, hwq, 4) < 4) + return IRQ_HANDLED; + + /* + * Defer further completion processing to thread context because + * processing a large number of completions in interrupt context on + * slower CPU cores can result in unacceptably high interrupt latencies= . + */ + return IRQ_WAKE_THREAD; } =20 static int ufs_qcom_config_esi(struct ufs_hba *hba) @@ -2415,8 +2438,10 @@ static int ufs_qcom_config_esi(struct ufs_hba *hba= ) qi[idx].idx =3D idx; qi[idx].hba =3D hba; =20 - ret =3D devm_request_irq(hba->dev, qi[idx].irq, ufs_qcom_mcq_esi_handl= er, - IRQF_SHARED, "qcom-mcq-esi", qi + idx); + ret =3D devm_request_threaded_irq(hba->dev, qi[idx].irq, + ufs_qcom_mcq_esi_handler, + ufs_qcom_mcq_threaded_esi_handler, + IRQF_SHARED | IRQF_ONESHOT, "qcom-mcq-esi", qi + idx); if (ret) { dev_err(hba->dev, "%s: Failed to request IRQ for %d, err =3D %d\n", __func__, qi[idx].irq, ret);