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[46.208.116.5]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4601f2ec711sm7254825f8f.12.2026.06.03.06.06.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Jun 2026 06:06:22 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" Authentication-Results: eu.smtp.expurgate.cloud; dkim=pass header.s=20251104 header.d=gmail.com header.i="@gmail.com" header.h="Content-Transfer-Encoding:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1780491983; x=1781096783; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=E0qnwksAnVibKLEOmCRSNsa6uG3n6snRRRntsiizK/M=; b=eQx3LonuUXFrPzTyJAaIk/3pbaBYDEEpcxmhIYjJny+3+3mQcZ07V90CwONr13OaRX 2RIfC0Ze2KXTAi9SdlaVTjkCgS1LxlAREJij80ZXMrfVDSo7d0X7zljF8UffnN7Tqshv 3q2UQDJfaUFxhFO+ZHTTQvhfmyjgGa5wyQ5kah3qRs4yflJ8wiJz1JSv4qRY2S49DraQ R0ySKf8q9mrzXbgiq+p6sG+ckBQNg3RnjP0at48eXPg2LkEEfXRzGKX0FcvsLrxTNWFh 8cPJ9ebAL/7KhX5mSPsdFLwXhm5ZufV6X1Jc7gfVFKSOyDSIveTk5gm1B1MI6sinRZG5 SSKw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780491983; x=1781096783; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=E0qnwksAnVibKLEOmCRSNsa6uG3n6snRRRntsiizK/M=; b=AP9RO2TNm8HIR8IUMHloCr9ceI2c6PulGxct+VJvR4qfse3h0Il8WbSe1Plvb/TOpF aWs8u96AM4s8LmHDfyrLtIjGWRx7PelySm7n5D1bPjA1MT1LC8Pp+VpRSFtpVXFFGG9X VdZ0DEr+AkFksG0NqCCMTjUjde87Jc1eFfPmcPy3UC+MYCLxoy7VGE9URB45wztjZUvF cgviu9dZwxlcuwqN/IzaOeWAT4MQRErcmsT4pRb3Qypmk+y6AB5t5h9bvKP4LOq3kouI HqN/nZP7F8AdfzpsnFd+wh7PX9NCg5y+5f3A467Sfp7+m06gv9SJVcyvd6ma+UwiDT/X eKsg== X-Gm-Message-State: AOJu0Yzv0sltLaPDeirgh6/nrESO6SGD3CVCunzJmafMsiQjaKyiNoV0 TgDKAphpcO7rUyUP0YNqsu2YNmSSJe8wtNxkYpfq2CGF/BaYut0ajImlVziA5UWW X-Gm-Gg: Acq92OHFEPQOpTGsmjzcyAcCPlfkvi0cEM7ZgCn/bCMEjiAj1/3xD7OxIiUa9e0L8sZ bhCwrfQCQPkk/Z4ApDiCENPUW8e6nnU+7Ire4QhN2stKzDYIMTbMnAuqBuRbAGBu71rBBe0jHCc +OiVktEPDR4vOO7etWG+Wz6DzY7K+mvN1uPbmF5mXXD74SHXR4GqUbNT27jcVSnAvAS2iFQEnZo x6e+mduoMnggaAkONs7S7Pt4lY6c4SwTVT5Fe+EfePnr6eKGkGQ3kJgO4IH8pKmPiyXd3NE6LUw AGbZTvN+zcn0zr6mVpcZFoC8mlDGtFErz4nW26YfU1k5ZuhQgtU8sohUs9wMjoVeQS78Gz/n+uM Te85IOa1ZexIVmSXx75zHXD66QT+nfCYg7B3XneRLGoJTkI6DRlPtozhHXHB3yXbUjrxw0pAZJD gHCx0c71Xmo55hs5teW5LHorjq7lrUugBcLeXuxO4O40wgIdmbUTgW/x7mhTlNos02spezJ0Jb5 /2Pu0vXdOGxH4D6OQmbgcymxb1vPlfsPv6L X-Received: by 2002:a5d:4987:0:b0:451:3b12:9bca with SMTP id ffacd0b85a97d-46021831001mr3701447f8f.25.1780491983000; Wed, 03 Jun 2026 06:06:23 -0700 (PDT) From: Frediano Ziglio X-Google-Original-From: Frediano Ziglio To: xen-devel@lists.xenproject.org Cc: =?UTF-8?q?Edwin=20T=C3=B6r=C3=B6k?= , Jan Beulich , Andrew Cooper , =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= , Teddy Astie , Anthony PERARD , Juergen Gross , Frediano Ziglio Subject: [PATCH v4 06/16] libs/call: cache up to 4 pages in hypercall bounce buffers Date: Wed, 3 Jun 2026 14:05:53 +0100 Message-ID: <20260603130603.776452-7-frediano.ziglio@cloud.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260603130603.776452-1-frediano.ziglio@cloud.com> References: <20260603130603.776452-1-frediano.ziglio@cloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-purgate-ID: tlsNG-d25034/1780491983-DAF72CF5-257ED0B1/0/0 X-purgate-type: clean X-purgate-size: 4973 From: Edwin Török During migration there are a lot of mmap/munmap calls, because `xc_get_pfn_type_batch` exceeds the default hypercall bounce buffer cache size, and needs to allocate every time it is called. `munmap` is slow, especially in a PV Dom0 (takes an emulation fault), so is best avoided. Eventually it'd be good if the memory pool from xmalloc_tlsf.c was reused here, but for now make it handle the commonly encountered sizes (so far up to 4 pages). Signed-off-by: Edwin Török Signed-off-by: Frediano Ziglio -- Changes since v2: - change prefix in subject. --- tools/libs/call/buffer.c | 28 +++++++++++++++++----------- tools/libs/call/core.c | 3 ++- tools/libs/call/private.h | 8 +++++--- 3 files changed, 24 insertions(+), 15 deletions(-) diff --git a/tools/libs/call/buffer.c b/tools/libs/call/buffer.c index 2579b8c719..15d2f98a6b 100644 --- a/tools/libs/call/buffer.c +++ b/tools/libs/call/buffer.c @@ -56,13 +56,13 @@ static void *cache_alloc(xencall_handle *xcall, size_t nr_pages) if ( xcall->buffer_current_allocations > xcall->buffer_maximum_allocations ) xcall->buffer_maximum_allocations = xcall->buffer_current_allocations; - if ( nr_pages > 1 ) + if ( nr_pages > ARRAY_SIZE(xcall->buffer_cache) ) { xcall->buffer_cache_toobig++; } - else if ( xcall->buffer_cache_nr > 0 ) + else if ( xcall->buffer_cache_nr[nr_pages-1] > 0 ) { - p = xcall->buffer_cache[--xcall->buffer_cache_nr]; + p = xcall->buffer_cache[nr_pages-1][--xcall->buffer_cache_nr[nr_pages-1]]; xcall->buffer_cache_hits++; } else @@ -84,10 +84,10 @@ static int cache_free(xencall_handle *xcall, void *p, size_t nr_pages) xcall->buffer_total_releases++; xcall->buffer_current_allocations--; - if ( nr_pages == 1 && - xcall->buffer_cache_nr < BUFFER_CACHE_SIZE ) + if ( nr_pages && nr_pages < ARRAY_SIZE(xcall->buffer_cache) && + xcall->buffer_cache_nr[nr_pages-1] < BUFFER_CACHE_SIZE ) { - xcall->buffer_cache[xcall->buffer_cache_nr++] = p; + xcall->buffer_cache[nr_pages-1][xcall->buffer_cache_nr[nr_pages-1]++] = p; rc = 1; } @@ -108,17 +108,23 @@ void buffer_release_cache(xencall_handle *xcall) DBGPRINTF("current allocations:%d maximum allocations:%d", xcall->buffer_current_allocations, xcall->buffer_maximum_allocations); - DBGPRINTF("cache current size:%d", - xcall->buffer_cache_nr); + for ( unsigned i = 0; i < ARRAY_SIZE(xcall->buffer_cache_nr); ++i ) + { + DBGPRINTF("cache current size[%u pages]:%d", i+1, + xcall->buffer_cache_nr[i]); + } DBGPRINTF("cache hits:%d misses:%d toobig:%d", xcall->buffer_cache_hits, xcall->buffer_cache_misses, xcall->buffer_cache_toobig); - while ( xcall->buffer_cache_nr > 0 ) + for ( unsigned i = 0; i < ARRAY_SIZE(xcall->buffer_cache_nr); ++i ) { - p = xcall->buffer_cache[--xcall->buffer_cache_nr]; - osdep_free_pages(xcall, p, 1); + while ( xcall->buffer_cache_nr[i] > 0 ) + { + p = xcall->buffer_cache[i][--xcall->buffer_cache_nr[i]]; + osdep_free_pages(xcall, p, i + 1); + } } cache_unlock(xcall); diff --git a/tools/libs/call/core.c b/tools/libs/call/core.c index 02c4f8e1ae..dd8877c1a0 100644 --- a/tools/libs/call/core.c +++ b/tools/libs/call/core.c @@ -14,6 +14,7 @@ */ #include +#include #include "private.h" @@ -44,7 +45,7 @@ xencall_handle *xencall_open(xentoollog_logger *logger, unsigned open_flags) xentoolcore__register_active_handle(&xcall->tc_ah); xcall->flags = open_flags; - xcall->buffer_cache_nr = 0; + memset(xcall->buffer_cache_nr, 0, sizeof(xcall->buffer_cache_nr)); xcall->buffer_total_allocations = 0; xcall->buffer_total_releases = 0; diff --git a/tools/libs/call/private.h b/tools/libs/call/private.h index 9c3aa432ef..8e6a208975 100644 --- a/tools/libs/call/private.h +++ b/tools/libs/call/private.h @@ -31,13 +31,15 @@ struct xencall_handle { Xentoolcore__Active_Handle tc_ah; /* - * A simple cache of unused, single page, hypercall buffers + * A simple cache of unused, small, hypercall buffers + * buffer_cache[i]'s size is (i+1) pages * * Protected by a global lock. */ #define BUFFER_CACHE_SIZE 4 - int buffer_cache_nr; - void *buffer_cache[BUFFER_CACHE_SIZE]; +#define BUFFER_CACHE_NRPAGES 4 + int buffer_cache_nr[BUFFER_CACHE_NRPAGES]; + void *buffer_cache[BUFFER_CACHE_NRPAGES][BUFFER_CACHE_SIZE]; /* * Hypercall buffer statistics. All protected by the global -- 2.54.0