From patchwork Fri Feb 16 13:15:57 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 874417 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3zjYbF123Yz9s72 for ; Sat, 17 Feb 2018 00:17:29 +1100 (AEDT) Received: from localhost ([::1]:48143 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emftH-0001Al-43 for incoming@patchwork.ozlabs.org; Fri, 16 Feb 2018 08:17:27 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51641) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emfsN-00018k-Bn for qemu-devel@nongnu.org; Fri, 16 Feb 2018 08:16:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1emfsL-0005Xp-M2 for qemu-devel@nongnu.org; Fri, 16 Feb 2018 08:16:31 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:35996 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1emfsL-0005XL-G0 for qemu-devel@nongnu.org; Fri, 16 Feb 2018 08:16:29 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2332C4027CDF for ; Fri, 16 Feb 2018 13:16:29 +0000 (UTC) Received: from dgilbert-t530.redhat.com (unknown [10.36.118.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id CEACC213AEE2; Fri, 16 Feb 2018 13:16:27 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, marcandre.lureau@redhat.com, peterx@redhat.com, imammedo@redhat.com, mst@redhat.com Date: Fri, 16 Feb 2018 13:15:57 +0000 Message-Id: <20180216131625.9639-2-dgilbert@redhat.com> In-Reply-To: <20180216131625.9639-1-dgilbert@redhat.com> References: <20180216131625.9639-1-dgilbert@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 16 Feb 2018 13:16:29 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.6]); Fri, 16 Feb 2018 13:16:29 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dgilbert@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v3 01/29] migrate: Update ram_block_discard_range for shared X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aarcange@redhat.com, quintela@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: "Dr. David Alan Gilbert" The choice of call to discard a block is getting more complicated for other cases. We use fallocate PUNCH_HOLE in any file cases; it works for both hugepage and for tmpfs. We use the DONTNEED for non-hugepage cases either where they're anonymous or where they're private. Care should be taken when trying other backing files. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Peter Xu --- exec.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++-------------- trace-events | 3 ++- 2 files changed, 48 insertions(+), 15 deletions(-) diff --git a/exec.c b/exec.c index e8d7b335b6..b1bb477776 100644 --- a/exec.c +++ b/exec.c @@ -3702,6 +3702,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) } if ((start + length) <= rb->used_length) { + bool need_madvise, need_fallocate; uint8_t *host_endaddr = host_startaddr + length; if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { error_report("ram_block_discard_range: Unaligned end address: %p", @@ -3711,29 +3712,60 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) errno = ENOTSUP; /* If we are missing MADVISE etc */ - if (rb->page_size == qemu_host_page_size) { -#if defined(CONFIG_MADVISE) - /* Note: We need the madvise MADV_DONTNEED behaviour of definitely - * freeing the page. - */ - ret = madvise(host_startaddr, length, MADV_DONTNEED); -#endif - } else { - /* Huge page case - unfortunately it can't do DONTNEED, but - * it can do the equivalent by FALLOC_FL_PUNCH_HOLE in the - * huge page file. + /* The logic here is messy; + * madvise DONTNEED fails for hugepages + * fallocate works on hugepages and shmem + */ + need_madvise = (rb->page_size == qemu_host_page_size); + need_fallocate = rb->fd != -1; + if (need_fallocate) { + /* For a file, this causes the area of the file to be zero'd + * if read, and for hugetlbfs also causes it to be unmapped + * so a userfault will trigger. */ #ifdef CONFIG_FALLOCATE_PUNCH_HOLE ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, start, length); + if (ret) { + ret = -errno; + error_report("ram_block_discard_range: Failed to fallocate " + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + goto err; + } +#else + ret = -ENOSYS; + error_report("ram_block_discard_range: fallocate not available/file" + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + goto err; #endif } - if (ret) { - ret = -errno; - error_report("ram_block_discard_range: Failed to discard range " + if (need_madvise) { + /* For normal RAM this causes it to be unmapped, + * for shared memory it causes the local mapping to disappear + * and to fall back on the file contents (which we just + * fallocate'd away). + */ +#if defined(CONFIG_MADVISE) + ret = madvise(host_startaddr, length, MADV_DONTNEED); + if (ret) { + ret = -errno; + error_report("ram_block_discard_range: Failed to discard range " + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + goto err; + } +#else + ret = -ENOSYS; + error_report("ram_block_discard_range: MADVISE not available" "%s:%" PRIx64 " +%zx (%d)", rb->idstr, start, length, ret); + goto err; +#endif } + trace_ram_block_discard_range(rb->idstr, host_startaddr, + need_madvise, need_fallocate, ret); } else { error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64 "/%zx/" RAM_ADDR_FMT")", diff --git a/trace-events b/trace-events index ec95e67089..bf9741d930 100644 --- a/trace-events +++ b/trace-events @@ -55,9 +55,10 @@ dma_complete(void *dbs, int ret, void *cb) "dbs=%p ret=%d cb=%p" dma_blk_cb(void *dbs, int ret) "dbs=%p ret=%d" dma_map_wait(void *dbs) "dbs=%p" -# # exec.c +# exec.c find_ram_offset(uint64_t size, uint64_t offset) "size: 0x%" PRIx64 " @ 0x%" PRIx64 find_ram_offset_loop(uint64_t size, uint64_t candidate, uint64_t offset, uint64_t next, uint64_t mingap) "trying size: 0x%" PRIx64 " @ 0x%" PRIx64 ", offset: 0x%" PRIx64" next: 0x%" PRIx64 " mingap: 0x%" PRIx64 +ram_block_discard_range(const char *rbname, void *hva, bool need_madvise, bool need_fallocate, int ret) "%s@%p: madvise: %d fallocate: %d ret: %d" # memory.c memory_region_ops_read(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"