From win-pv-devel-bounces@lists.xenproject.org Thu Aug 06 07:45:55 2026 Return-path: Envelope-to: archives@lists.xenproject.org Delivery-date: Thu, 06 Aug 2026 07:45:55 +0000 Received: from list by lists.xenproject.org with outflank-mailman.1384294.1627303 (Exim 4.92) (envelope-from ) id 1wrsna-00011Q-3G; Thu, 06 Aug 2026 07:45:54 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1384294.1627303; Thu, 06 Aug 2026 07:45:54 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1wrsna-00011J-0f; Thu, 06 Aug 2026 07:45:54 +0000 Received: by outflank-mailman (input) for mailman id 1384294; Thu, 06 Aug 2026 07:45:52 +0000 Received: from mx.expurgate.net ([195.190.135.20]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1wrsnY-00011D-GL for win-pv-devel@lists.xenproject.org; Thu, 06 Aug 2026 07:45:52 +0000 Received: from mx.expurgate.net (helo=localhost) by mx.expurgate.net with esmtp id 1wrsnX-00C3bg-AA for win-pv-devel@lists.xenproject.org; Thu, 06 Aug 2026 09:45:51 +0200 Received: from [10.42.69.2] (helo=localhost) by localhost with ESMTP (eXpurgate MTA 0.9.1) (envelope-from ) id 6a743ba4-2eae-0a2a0a5409dd-0a2a4502cf66-36 for ; Thu, 06 Aug 2026 09:45:51 +0200 Received: from [160.101.131.8] (helo=na1pdmzitismtp01.tibco.com) by tlsNG-720697.mxtls.expurgate.net with ESMTPS (eXpurgate 4.57.1) (envelope-from ) id 6a743bae-6ca4-0a2a45020019-a0658308b736-3 for ; Thu, 06 Aug 2026 09:45:51 +0200 Received: from mewpvdipd2033.citrite.net (unknown [10.113.48.64]) by na1pdmzitismtp01.tibco.com (Postfix) with ESMTP id C4038449C9FC; Thu, 6 Aug 2026 03:44:11 -0400 (EDT) X-BeenThere: win-pv-devel@lists.xenproject.org List-Id: Developer list for the Windows PV Drivers subproject List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: win-pv-devel-bounces@lists.xenproject.org Precedence: list Sender: "win-pv-devel" Authentication-Results: eu.smtp.expurgate.cloud; none From: Owen Smith To: win-pv-devel@lists.xenproject.org Cc: Owen Smith Subject: [PATCH 1/2] Remove redundant RtlZeroMemory on CacheCreateSlab Date: Thu, 6 Aug 2026 08:45:44 +0100 Message-ID: <20260806074545.990-1-owen.smith@citrix.com> X-Mailer: git-send-email 2.51.2.windows.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-purgate-ID: tlsNG-720697/1786002351-67ABD2AC-F4FE41BE/0/0 X-purgate-type: clean X-purgate-size: 595 __CacheAllocate already returns zeroed memory, it is redundant to call RtlZeroMemory after allocation. Signed-off-by: Owen Smith --- src/xenbus/cache.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/src/xenbus/cache.c b/src/xenbus/cache.c index eb7020d..81cd3eb 100644 --- a/src/xenbus/cache.c +++ b/src/xenbus/cache.c @@ -424,8 +424,6 @@ CacheCreateSlab( if (Slab == NULL) goto fail2; - RtlZeroMemory(Slab, NumberOfBytes); - Slab->Magic = XENBUS_CACHE_SLAB_MAGIC; Slab->Cache = Cache; -- 2.51.2.windows.1 From win-pv-devel-bounces@lists.xenproject.org Thu Aug 06 07:45:56 2026 Return-path: Envelope-to: archives@lists.xenproject.org Delivery-date: Thu, 06 Aug 2026 07:45:56 +0000 Received: from list by lists.xenproject.org with outflank-mailman.1384295.1627307 (Exim 4.92) (envelope-from ) id 1wrsnc-00012n-4P; Thu, 06 Aug 2026 07:45:56 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1384295.1627307; Thu, 06 Aug 2026 07:45:56 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1wrsnc-00012g-1q; Thu, 06 Aug 2026 07:45:56 +0000 Received: by outflank-mailman (input) for mailman id 1384295; Thu, 06 Aug 2026 07:45:54 +0000 Received: from mx.expurgate.net ([195.190.135.20]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1wrsna-00012S-LT for win-pv-devel@lists.xenproject.org; Thu, 06 Aug 2026 07:45:54 +0000 Received: from mx.expurgate.net (helo=localhost) by mx.expurgate.net with esmtp id 1wrsna-00C3bg-1d for win-pv-devel@lists.xenproject.org; Thu, 06 Aug 2026 09:45:54 +0200 Received: from [10.42.69.11] (helo=localhost) by localhost with ESMTP (eXpurgate MTA 0.9.1) (envelope-from ) id 6a743bb0-2eae-0a2a0a5409dd-0a2a450b9bc6-10 for ; Thu, 06 Aug 2026 09:45:53 +0200 Received: from [160.101.131.8] (helo=na1pdmzitismtp01.tibco.com) by tlsNG-42698a.mxtls.expurgate.net with ESMTPS (eXpurgate 4.57.1) (envelope-from ) id 6a743bb0-b7e8-0a2a450b0019-a06583088706-3 for ; Thu, 06 Aug 2026 09:45:53 +0200 Received: from mewpvdipd2033.citrite.net (unknown [10.113.48.64]) by na1pdmzitismtp01.tibco.com (Postfix) with ESMTP id 7780D449C9FC; Thu, 6 Aug 2026 03:44:14 -0400 (EDT) X-BeenThere: win-pv-devel@lists.xenproject.org List-Id: Developer list for the Windows PV Drivers subproject List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: win-pv-devel-bounces@lists.xenproject.org Precedence: list Sender: "win-pv-devel" Authentication-Results: eu.smtp.expurgate.cloud; none From: Owen Smith To: win-pv-devel@lists.xenproject.org Cc: Owen Smith Subject: [PATCH 2/2] cache: Dont linearly scan magazine slots for objects Date: Thu, 6 Aug 2026 08:45:45 +0100 Message-ID: <20260806074545.990-2-owen.smith@citrix.com> X-Mailer: git-send-email 2.51.2.windows.1 In-Reply-To: <20260806074545.990-1-owen.smith@citrix.com> References: <20260806074545.990-1-owen.smith@citrix.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-purgate-ID: tlsNG-42698a/1786002353-ABCD79EA-2C9EC072/0/0 X-purgate-type: clean X-purgate-size: 2323 Add an occupancy count to the cache magazine, and use this as an index into the magazine slots for the current get/put location. This avoids a linear scan of magazine slots when looking for a valid slot during CacheGetObjectFromMagazine or CachePutObjectToMagazine, reducing the algorithm from O(n) to O(1). Signed-off-by: Owen Smith --- src/xenbus/cache.c | 34 +++++++++++++++------------------- 1 file changed, 15 insertions(+), 19 deletions(-) diff --git a/src/xenbus/cache.c b/src/xenbus/cache.c index 81cd3eb..90aea08 100644 --- a/src/xenbus/cache.c +++ b/src/xenbus/cache.c @@ -50,6 +50,7 @@ RtlRandomEx ( #define XENBUS_CACHE_MAGAZINE_SLOTS 6 typedef struct _XENBUS_CACHE_MAGAZINE { + ULONG Count; PVOID Slot[XENBUS_CACHE_MAGAZINE_SLOTS]; } XENBUS_CACHE_MAGAZINE, *PXENBUS_CACHE_MAGAZINE; @@ -167,20 +168,16 @@ CacheGetObjectFromMagazine( _In_ PXENBUS_CACHE_MAGAZINE Magazine ) { - ULONG Index; - - for (Index = 0; Index < XENBUS_CACHE_MAGAZINE_SLOTS; Index++) { - PVOID Object; + PVOID Object; - if (Magazine->Slot[Index] != NULL) { - Object = Magazine->Slot[Index]; - Magazine->Slot[Index] = NULL; + if (Magazine->Count == 0) + return NULL; - return Object; - } - } + Object = Magazine->Slot[--Magazine->Count]; + Magazine->Slot[Magazine->Count] = NULL; - return NULL; + ASSERT(Object != NULL); + return Object; } static NTSTATUS @@ -189,16 +186,15 @@ CachePutObjectToMagazine( _In_ PVOID Object ) { - ULONG Index; + ASSERT(Object != NULL); - for (Index = 0; Index < XENBUS_CACHE_MAGAZINE_SLOTS; Index++) { - if (Magazine->Slot[Index] == NULL) { - Magazine->Slot[Index] = Object; - return STATUS_SUCCESS; - } - } + if (Magazine->Count == XENBUS_CACHE_MAGAZINE_SLOTS) + return STATUS_UNSUCCESSFUL; + + ASSERT(Magazine->Slot[Magazine->Count] == NULL); + Magazine->Slot[Magazine->Count++] = Object; - return STATUS_UNSUCCESSFUL; + return STATUS_SUCCESS; } static PXENBUS_CACHE_MASK -- 2.51.2.windows.1 From win-pv-devel-bounces@lists.xenproject.org Fri Aug 07 11:42:49 2026 Return-path: Envelope-to: archives@lists.xenproject.org Delivery-date: Fri, 07 Aug 2026 11:42:49 +0000 Received: from list by lists.xenproject.org with outflank-mailman.1385962.1628232 (Exim 4.92) (envelope-from ) id 1wsIyN-0002am-Tz; Fri, 07 Aug 2026 11:42:47 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1385962.1628232; 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boundary="-=Part.1ec3.8512d480895ce444.19fdc0854c5.7ff25471dfd26c09=-" X-Bm-Milter-Handled: 4ffbd6c1-ee69-4e1b-aabd-f977039bd3e2 X-Bm-Transport-Timestamp: 1786102961350 X-purgate-ID: tlsNG-720697/1786102964-323D42AC-41C672EC/0/0 X-purgate-type: clean X-purgate-size: 1094 ---=Part.1ec3.8512d480895ce444.19fdc0854c5.7ff25471dfd26c09=- Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06/08/2026 09:46, Owen Smith wrote: > __CacheAllocate already returns zeroed memory, it is redundant to > call RtlZeroMemory after allocation=2E >=20 > Signed-off-by: Owen Smith Reviewed-by: Tu Dinh > --- > src/xenbus/cache=2Ec | 2 -- > 1 file changed, 2 deletions(-) >=20 > diff --git a/src/xenbus/cache=2Ec b/src/xenbus/cache=2Ec > index eb7020d=2E=2E81cd3eb 100644 > --- a/src/xenbus/cache=2Ec > +++ b/src/xenbus/cache=2Ec > @@ -424,8 +424,6 @@ CacheCreateSlab( > if (Slab =3D=3D NULL) > goto fail2; > =20 > - RtlZeroMemory(Slab, NumberOfBytes); > - > Slab->Magic =3D XENBUS_CACHE_SLAB_MAGIC; > Slab->Cache =3D Cache; > =20 -- Ngoc Tu Dinh | Vates XCP-ng Developer XCP-ng & Xen Orchestra - Vates = solutions web: https://vates=2Etech ---=Part.1ec3.8512d480895ce444.19fdc0854c5.7ff25471dfd26c09=--- From win-pv-devel-bounces@lists.xenproject.org Fri Aug 07 11:43:01 2026 Return-path: Envelope-to: archives@lists.xenproject.org Delivery-date: Fri, 07 Aug 2026 11:43:01 +0000 Received: from list by lists.xenproject.org with outflank-mailman.1385963.1628236 (Exim 4.92) (envelope-from ) id 1wsIya-0002d9-V5; Fri, 07 Aug 2026 11:43:00 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 1385963.1628236; Fri, 07 Aug 2026 11:43:00 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1wsIya-0002d2-Sa; Fri, 07 Aug 2026 11:43:00 +0000 Received: by outflank-mailman (input) for mailman id 1385963; Fri, 07 Aug 2026 11:43:00 +0000 Received: from mx.expurgate.net ([195.190.135.20]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1wsIyZ-0002cs-Ss for win-pv-devel@lists.xenproject.org; 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Fri, 7 Aug 2026 13:42:53 +0200 (CEST) X-BeenThere: win-pv-devel@lists.xenproject.org List-Id: Developer list for the Windows PV Drivers subproject List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: win-pv-devel-bounces@lists.xenproject.org Precedence: list Sender: "win-pv-devel" Authentication-Results: eu.smtp.expurgate.cloud; dkim=pass header.s=selector1 header.d=vates.tech header.i="@vates.tech" header.h="From:Subject:Date:Message-ID:To:MIME-Version:Content-Type:In-Reply-To:References:Feedback-ID" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vates.tech; q=dns/txt; s=selector1; bh=4oNqW41O3vWqXQjSUHyNrstUx4aWL4sKydfoctQjWW0=; h=from:subject:date:message-id:to:mime-version:content-type:in-reply-to:references:feedback-id; b=N2C9u1Ta4JOE8kDiOinJhWuW8Unw9VK+M2SBzLjeUqppK9zvKVZaYGyXTblJq1vYAJiGKb0hX z6jsVieMNxjvx07oO7yROvehaDgTZD5uB10o4KtK2PIq3aVVqyaIA+KvpSfxrlq2F2sW9Q4WmNn zNYnBlFoLYQ6ymJuSN3cycd5FD4AaBuwYm04bYzCLMGLcUCs5uMv3ZKuNtZhHcVL3B6JgYVP8Ue B3u/bMGwgUiAXlIbcaUDoYs+3RJgis9/cIqIoDZUPuBlShB/IydPDEAhT1A3mQaO3hEw3oMAzcF af0kZU8W2VZHVtQufzJ4QTioQVvZ6fWX6mjs+ady11kw== X-Zone-Loop: c3fd75bc93e65b013d818292aaf88e05f9b1e23014ad x-campaign-type: default x-transaction-id: bbbb7337-f874-4611-8d8a-4b945c457179 x-swg-uid: 01-db8de2c5-6325-4077-9c55-7339090d6845 X-Mailer: Sweego Message-ID: <1786102974.8631fc262581453bbf619ec5b2062170.19fdc088618000e099@vates.tech> x-swg-bid: 1786102974.8631fc262581453bbf619ec5b2062170.19fdc088618000e099 Feedback-ID: default:8631fc262581453bbf619ec5b2062170:Sweego x-campaign-id: default x-client-id: 8631fc262581453bbf619ec5b2062170 X-Originating-IP: [37.26.189.201] Date: Fri, 7 Aug 2026 13:42:53 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] cache: Dont linearly scan magazine slots for objects To: Owen Smith , win-pv-devel@lists.xenproject.org References: <20260806074545.990-1-owen.smith@citrix.com> <20260806074545.990-2-owen.smith@citrix.com> Content-Language: en-US From: Tu Dinh In-Reply-To: <20260806074545.990-2-owen.smith@citrix.com> X-BM-Disclaimer: Yes Content-Type: multipart/alternative; boundary="-=Part.1ec4.8e6f9ec076ee174a.19fdc0883dd.8fc0e836ba848f28=-" X-Bm-Milter-Handled: 4ffbd6c1-ee69-4e1b-aabd-f977039bd3e2 X-Bm-Transport-Timestamp: 1786102973405 X-purgate-ID: tlsNG-d62444/1786102979-C5146757-12821EAF/0/0 X-purgate-type: clean X-purgate-size: 2993 ---=Part.1ec4.8e6f9ec076ee174a.19fdc0883dd.8fc0e836ba848f28=- Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 06/08/2026 09:46, Owen Smith wrote: > Add an occupancy count to the cache magazine, and use this as an index > into the magazine slots for the current get/put location=2E > This avoids a linear scan of magazine slots when looking for a valid > slot during CacheGetObjectFromMagazine or CachePutObjectToMagazine, > reducing the algorithm from O(n) to O(1)=2E >=20 > Signed-off-by: Owen Smith Reviewed-by: Tu Dinh > --- > src/xenbus/cache=2Ec | 34 +++++++++++++++------------------- > 1 file changed, 15 insertions(+), 19 deletions(-) >=20 > diff --git a/src/xenbus/cache=2Ec b/src/xenbus/cache=2Ec > index 81cd3eb=2E=2E90aea08 100644 > --- a/src/xenbus/cache=2Ec > +++ b/src/xenbus/cache=2Ec > @@ -50,6 +50,7 @@ RtlRandomEx ( > #define XENBUS_CACHE_MAGAZINE_SLOTS 6 > =20 > typedef struct _XENBUS_CACHE_MAGAZINE { > + ULONG Count; > PVOID Slot[XENBUS_CACHE_MAGAZINE_SLOTS]; > } XENBUS_CACHE_MAGAZINE, *PXENBUS_CACHE_MAGAZINE; > =20 > @@ -167,20 +168,16 @@ CacheGetObjectFromMagazine( > _In_ PXENBUS_CACHE_MAGAZINE Magazine > ) > { > - ULONG Index; > - > - for (Index =3D 0; Index < XENBUS_CACHE_MAGAZINE_SLOTS; Index++) { > - PVOID Object; > + PVOID Object; > =20 > - if (Magazine->Slot[Index] !=3D NULL) { > - Object =3D Magazine->Slot[Index]; > - Magazine->Slot[Index] =3D NULL; > + if (Magazine->Count =3D=3D 0) > + return NULL; > =20 > - return Object; > - } > - } > + Object =3D Magazine->Slot[--Magazine->Count]; > + Magazine->Slot[Magazine->Count] =3D NULL; > =20 > - return NULL; > + ASSERT(Object !=3D NULL); > + return Object; > } > =20 > static NTSTATUS > @@ -189,16 +186,15 @@ CachePutObjectToMagazine( > _In_ PVOID Object > ) > { > - ULONG Index; > + ASSERT(Object !=3D NULL); > =20 > - for (Index =3D 0; Index < XENBUS_CACHE_MAGAZINE_SLOTS; Index++) { > - if (Magazine->Slot[Index] =3D=3D NULL) { > - Magazine->Slot[Index] =3D Object; > - return STATUS_SUCCESS; > - } > - } > + if (Magazine->Count =3D=3D XENBUS_CACHE_MAGAZINE_SLOTS) > + return STATUS_UNSUCCESSFUL; > + > + ASSERT(Magazine->Slot[Magazine->Count] =3D=3D NULL); > + Magazine->Slot[Magazine->Count++] =3D Object; > =20 > - return STATUS_UNSUCCESSFUL; > + return STATUS_SUCCESS; > } > =20 > static PXENBUS_CACHE_MASK -- Ngoc Tu Dinh | Vates XCP-ng Developer XCP-ng & Xen Orchestra - Vates = solutions web: https://vates=2Etech ---=Part.1ec4.8e6f9ec076ee174a.19fdc0883dd.8fc0e836ba848f28=---