0dde13a5cd
- kvm-s390x-Fix-leak-in-machine_set_loadparm.patch [RHEL-98555] - kvm-hw-s390x-ccw-device-Fix-memory-leak-in-loadparm-sett.patch [RHEL-98555] - kvm-target-i386-Update-EPYC-CPU-model-for-Cache-property.patch [RHEL-52650] - kvm-target-i386-Update-EPYC-Rome-CPU-model-for-Cache-pro.patch [RHEL-52650] - kvm-target-i386-Update-EPYC-Milan-CPU-model-for-Cache-pr.patch [RHEL-52650] - kvm-target-i386-Add-couple-of-feature-bits-in-CPUID_Fn80.patch [RHEL-52650] - kvm-target-i386-Update-EPYC-Genoa-for-Cache-property-per.patch [RHEL-52650] - kvm-target-i386-Add-support-for-EPYC-Turin-model.patch [RHEL-52650] - kvm-include-qemu-compiler-add-QEMU_UNINITIALIZED-attribu.patch [RHEL-95479] - kvm-hw-virtio-virtio-avoid-cost-of-ftrivial-auto-var-ini.patch [RHEL-95479] - kvm-block-skip-automatic-zero-init-of-large-array-in-ioq.patch [RHEL-95479] - kvm-chardev-char-fd-skip-automatic-zero-init-of-large-ar.patch [RHEL-95479] - kvm-chardev-char-pty-skip-automatic-zero-init-of-large-a.patch [RHEL-95479] - kvm-chardev-char-socket-skip-automatic-zero-init-of-larg.patch [RHEL-95479] - kvm-hw-audio-ac97-skip-automatic-zero-init-of-large-arra.patch [RHEL-95479] - kvm-hw-audio-cs4231a-skip-automatic-zero-init-of-large-a.patch [RHEL-95479] - kvm-hw-audio-es1370-skip-automatic-zero-init-of-large-ar.patch [RHEL-95479] - kvm-hw-audio-gus-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-hw-audio-marvell_88w8618-skip-automatic-zero-init-of.patch [RHEL-95479] - kvm-hw-audio-sb16-skip-automatic-zero-init-of-large-arra.patch [RHEL-95479] - kvm-hw-audio-via-ac97-skip-automatic-zero-init-of-large-.patch [RHEL-95479] - kvm-hw-char-sclpconsole-lm-skip-automatic-zero-init-of-l.patch [RHEL-95479] - kvm-hw-dma-xlnx_csu_dma-skip-automatic-zero-init-of-larg.patch [RHEL-95479] - kvm-hw-display-vmware_vga-skip-automatic-zero-init-of-la.patch [RHEL-95479] - kvm-hw-hyperv-syndbg-skip-automatic-zero-init-of-large-a.patch [RHEL-95479] - kvm-hw-misc-aspeed_hace-skip-automatic-zero-init-of-larg.patch [RHEL-95479] - kvm-hw-net-rtl8139-skip-automatic-zero-init-of-large-arr.patch [RHEL-95479] - kvm-hw-net-tulip-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-hw-net-virtio-net-skip-automatic-zero-init-of-large-.patch [RHEL-95479] - kvm-hw-net-xgamc-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-hw-nvme-ctrl-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-hw-ppc-pnv_occ-skip-automatic-zero-init-of-large-str.patch [RHEL-95479] - kvm-hw-ppc-spapr_tpm_proxy-skip-automatic-zero-init-of-l.patch [RHEL-95479] - kvm-hw-usb-hcd-ohci-skip-automatic-zero-init-of-large-ar.patch [RHEL-95479] - kvm-hw-scsi-lsi53c895a-skip-automatic-zero-init-of-large.patch [RHEL-95479] - kvm-hw-scsi-megasas-skip-automatic-zero-init-of-large-ar.patch [RHEL-95479] - kvm-hw-ufs-lu-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-net-socket-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-net-stream-skip-automatic-zero-init-of-large-array.patch [RHEL-95479] - kvm-hw-i386-amd_iommu-Isolate-AMDVI-PCI-from-amd-iommu-d.patch [RHEL-85649] - kvm-hw-i386-amd_iommu-Allow-migration-when-explicitly-cr.patch [RHEL-85649] - kvm-Enable-amd-iommu-device.patch [RHEL-85649] - kvm-ui-vnc-Update-display-update-interval-when-VM-state-.patch [RHEL-83883] - Resolves: RHEL-98555 ([s390x][RHEL10.1][ccw-device] there would be memory leak with virtio_blk disks) - Resolves: RHEL-52650 ([AMDSERVER 10.1 Feature] Turin: Qemu EPYC-Turin Model) - Resolves: RHEL-95479 (-ftrivial-auto-var-init=zero reduced performance) - Resolves: RHEL-85649 ([RHEL 10]Qemu/amd-iommu: Add ability to manually specify the AMDVI-PCI device) - Resolves: RHEL-83883 (Video stuck after switchover phase when play one video during migration)
73 lines
2.9 KiB
Diff
73 lines
2.9 KiB
Diff
From a39a353ec7656ef7a805391270cec24dfa815b7d Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>
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Date: Tue, 10 Jun 2025 13:37:01 +0100
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Subject: [PATCH 31/43] hw/nvme/ctrl: skip automatic zero-init of large arrays
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
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RH-MergeRequest: 381: Solve -ftrivial-auto-var-init performance regression with QEMU_UNINITIALIZED
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RH-Jira: RHEL-95479
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [23/31] 926fb489c480ad10c8560efa934b8a7fb3e7a8a3 (stefanha/centos-stream-qemu-kvm)
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The 'nvme_map_sgl' method has a 256 element array used for copying
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data from the device. Skip the automatic zero-init of this array
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to eliminate the performance overhead in the I/O hot path.
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The 'segment' array will be fully initialized when reading data from
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the device.
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The 'nme_changed_nslist' method has a 4k byte array that is manually
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initialized with memset(). The compiler ought to be intelligent
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enough to turn the memset() into a static initialization operation,
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and thus not duplicate the automatic zero-init. Replacing memset()
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with '{}' makes it unambiguous that the array is statically initialized.
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Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
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Message-id: 20250610123709.835102-24-berrange@redhat.com
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 7eeb1d3acc175813ad3d5e824f26123e0992093a)
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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hw/nvme/ctrl.c | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
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index d6b77d4fbc..ad6b264933 100644
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--- a/hw/nvme/ctrl.c
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+++ b/hw/nvme/ctrl.c
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@@ -1057,7 +1057,8 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, NvmeSg *sg, NvmeSglDescriptor sgl,
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*/
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#define SEG_CHUNK_SIZE 256
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- NvmeSglDescriptor segment[SEG_CHUNK_SIZE], *sgld, *last_sgld;
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+ QEMU_UNINITIALIZED NvmeSglDescriptor segment[SEG_CHUNK_SIZE];
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+ NvmeSglDescriptor *sgld, *last_sgld;
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uint64_t nsgld;
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uint32_t seg_len;
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uint16_t status;
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@@ -5128,7 +5129,7 @@ static uint16_t nvme_error_info(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
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static uint16_t nvme_changed_nslist(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
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uint64_t off, NvmeRequest *req)
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{
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- uint32_t nslist[1024];
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+ uint32_t nslist[1024] = {};
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uint32_t trans_len;
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int i = 0;
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uint32_t nsid;
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@@ -5138,7 +5139,6 @@ static uint16_t nvme_changed_nslist(NvmeCtrl *n, uint8_t rae, uint32_t buf_len,
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return NVME_INVALID_FIELD | NVME_DNR;
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}
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- memset(nslist, 0x0, sizeof(nslist));
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trans_len = MIN(sizeof(nslist) - off, buf_len);
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while ((nsid = find_first_bit(n->changed_nsids, NVME_CHANGED_NSID_SIZE)) !=
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--
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2.39.3
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