From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:41024) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T1f89-0008SW-1R for qemu-devel@nongnu.org; Wed, 15 Aug 2012 11:03:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T1f84-0007zm-GO for qemu-devel@nongnu.org; Wed, 15 Aug 2012 11:03:32 -0400 Received: from isrv.corpit.ru ([86.62.121.231]:51142) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T1f84-0007zi-3p for qemu-devel@nongnu.org; Wed, 15 Aug 2012 11:03:28 -0400 Message-ID: <502BBA3C.70506@msgid.tls.msk.ru> Date: Wed, 15 Aug 2012 19:03:24 +0400 From: Michael Tokarev MIME-Version: 1.0 References: <502B99D0.8010808@msgid.tls.msk.ru> <502B9B40.6090307@redhat.com> <502BB0C2.3040701@msgid.tls.msk.ru> <502BB1A6.7030407@redhat.com> In-Reply-To: <502BB1A6.7030407@redhat.com> Content-Type: multipart/mixed; boundary="------------080708010602050204080305" Subject: Re: [Qemu-devel] qemu and transparent huge pages List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Andrea Arcangeli , qemu-devel This is a multi-part message in MIME format. --------------080708010602050204080305 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 15.08.2012 18:26, Avi Kivity wrote: > On 08/15/2012 05:22 PM, Michael Tokarev wrote: > >>> >>> Please provide extra info, like the setting of >>> /sys/kernel/mm/transparent_hugepage/enabled. >> >> That was it - sort of. Default value here is enabled=madvise. >> When setting it to always the effect finally started appearing, >> so it is actually working. >> >> But can't qemu set MADV_HUGEPAGE flag too, so it works automatically? > > It can and should. Something like the attached patch? Thanks, /mjt --------------080708010602050204080305 Content-Type: text/x-patch; name="0001-mark-large-vmalloc-areas-as-MADV_HUGEPAGE-and-allow-.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename*0="0001-mark-large-vmalloc-areas-as-MADV_HUGEPAGE-and-allow-.pa"; filename*1="tch" >>From 705b3efb8c0cf06cbf087204fc61863c2bbb9e27 Mon Sep 17 00:00:00 2001 From: Michael Tokarev Date: Wed, 15 Aug 2012 18:55:16 +0400 Subject: [PATCH] mark large vmalloc areas as MADV_HUGEPAGE and allow hugepages on i386 A followup to commit 36b586284e678d. On linux only (which supports transparent hugepages), explicitly mark large vmalloced areas with madvise(MADV_HUGEPAGES). The patch changes previous logic a bit to allow inserting the call to madvise(), but keeps the code the same (and saves one call to getpagesize() per allocation). The code also adds #include to the linux-specific part, to get MADV_HUGEPAGES definition. While at it, enable transparent hugepages (alignment and the new explicit marking with madvise()) for 32bit x86 too - it makes good sense for, say, 32bit userspace on 64bit kernel. Signed-off-by: Michael Tokarev --- oslib-posix.c | 35 +++++++++++++++++++++++++---------- 1 file changed, 25 insertions(+), 10 deletions(-) diff --git a/oslib-posix.c b/oslib-posix.c index dbeb627..ab32d6d 100644 --- a/oslib-posix.c +++ b/oslib-posix.c @@ -35,19 +35,23 @@ extern int daemon(int, int); #endif -#if defined(__linux__) && defined(__x86_64__) +#ifdef __linux__ +# include + +# if defined(__x86_64__) || defined(__i386__) /* Use 2 MiB alignment so transparent hugepages can be used by KVM. Valgrind does not support alignments larger than 1 MiB, therefore we need special code which handles running on Valgrind. */ -# define QEMU_VMALLOC_ALIGN (512 * 4096) +# define QEMU_VMALLOC_ALIGN_HUGE (512 * 4096) # define CONFIG_VALGRIND -#elif defined(__linux__) && defined(__s390x__) +# elif defined(__s390x__) /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */ -# define QEMU_VMALLOC_ALIGN (256 * 4096) -#else -# define QEMU_VMALLOC_ALIGN getpagesize() +# define QEMU_VMALLOC_ALIGN_HUGE (256 * 4096) +# endif #endif +#define QEMU_VMALLOC_ALIGN getpagesize() + #include "config-host.h" #include "sysemu.h" #include "trace.h" @@ -114,7 +118,6 @@ void *qemu_memalign(size_t alignment, size_t size) void *qemu_vmalloc(size_t size) { void *ptr; - size_t align = QEMU_VMALLOC_ALIGN; #if defined(CONFIG_VALGRIND) if (running_on_valgrind < 0) { @@ -125,10 +128,22 @@ void *qemu_vmalloc(size_t size) } #endif - if (size < align || running_on_valgrind) { - align = getpagesize(); +#ifdef QEMU_VMALLOC_ALIGN_HUGE + /* try to allocate as huge pages if supported and large enough */ + if (size >= QEMU_VMALLOC_ALIGN_HUGE && !running_on_valgrind) { + ptr = qemu_memalign(QEMU_VMALLOC_ALIGN_HUGE, size); +#ifdef MADV_HUGEPAGE +#error + qemu_madvise(ptr, size, MADV_HUGEPAGE); +#endif } - ptr = qemu_memalign(align, size); + else +#endif + { + /* if unsupported or small, allocate pagesize-aligned */ + ptr = qemu_memalign(QEMU_VMALLOC_ALIGN, size); + } + trace_qemu_vmalloc(size, ptr); return ptr; } -- 1.7.10.4 --------------080708010602050204080305--