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block_util: Use SmallVec for I/O requests

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The number of buffers in the request is usually one so by using SmallVec
the number of heap allocations can be significantly reduced.

DHAT reports:

Before:

dhat: Total:     1,166,412 bytes in 40,383 blocks

After:

dhat: Total:     623,852 bytes in 8,157 blocks

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford
2023-01-10 12:45:30 +00:00
parent e7a51cde78
commit 67ff0d7819
3 changed files with 7 additions and 3 deletions
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Cargo.lock
Generated
+1
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@@ -88,6 +88,7 @@ dependencies = [
"libc", "libc",
"log", "log",
"qcow", "qcow",
"smallvec",
"thiserror", "thiserror",
"versionize", "versionize",
"versionize_derive", "versionize_derive",
block_util/Cargo.toml
+1
View File
@@ -12,6 +12,7 @@ io-uring = "0.5.9"
libc = "0.2.139" libc = "0.2.139"
log = "0.4.17" log = "0.4.17"
qcow = { path = "../qcow" } qcow = { path = "../qcow" }
smallvec = "1.10.0"
thiserror = "1.0.37" thiserror = "1.0.37"
versionize = "0.1.9" versionize = "0.1.9"
versionize_derive = "0.1.4" versionize_derive = "0.1.4"
block_util/src/lib.rs
+5 -3
View File
@@ -22,6 +22,7 @@ pub mod vhdx_sync;
use crate::async_io::{AsyncIo, AsyncIoError, AsyncIoResult}; use crate::async_io::{AsyncIo, AsyncIoError, AsyncIoResult};
use io_uring::{opcode, IoUring, Probe}; use io_uring::{opcode, IoUring, Probe};
use smallvec::SmallVec;
use std::alloc::{alloc_zeroed, dealloc, Layout}; use std::alloc::{alloc_zeroed, dealloc, Layout};
use std::cmp; use std::cmp;
use std::convert::TryInto; use std::convert::TryInto;
@@ -195,7 +196,7 @@ pub struct AlignedOperation {
pub struct Request { pub struct Request {
pub request_type: RequestType, pub request_type: RequestType,
pub sector: u64, pub sector: u64,
pub data_descriptors: Vec<(GuestAddress, u32)>, pub data_descriptors: SmallVec<[(GuestAddress, u32); 1]>,
pub status_addr: GuestAddress, pub status_addr: GuestAddress,
pub writeback: bool, pub writeback: bool,
pub aligned_operations: Vec<AlignedOperation>, pub aligned_operations: Vec<AlignedOperation>,
@@ -226,7 +227,7 @@ impl Request {
let mut req = Request { let mut req = Request {
request_type: request_type(desc_chain.memory(), hdr_desc_addr)?, request_type: request_type(desc_chain.memory(), hdr_desc_addr)?,
sector: sector(desc_chain.memory(), hdr_desc_addr)?, sector: sector(desc_chain.memory(), hdr_desc_addr)?,
data_descriptors: Vec::new(), data_descriptors: SmallVec::with_capacity(1),
status_addr: GuestAddress(0), status_addr: GuestAddress(0),
writeback: true, writeback: true,
aligned_operations: Vec::new(), aligned_operations: Vec::new(),
@@ -354,7 +355,8 @@ impl Request {
let request_type = self.request_type; let request_type = self.request_type;
let offset = (sector << SECTOR_SHIFT) as libc::off_t; let offset = (sector << SECTOR_SHIFT) as libc::off_t;
let mut iovecs = Vec::with_capacity(self.data_descriptors.len()); let mut iovecs: SmallVec<[libc::iovec; 1]> =
SmallVec::with_capacity(self.data_descriptors.len());
for (data_addr, data_len) in &self.data_descriptors { for (data_addr, data_len) in &self.data_descriptors {
if *data_len == 0 { if *data_len == 0 {
continue; continue;